Organometallic compound, organic light-emitting device including the organometallic compound, and diagnostic composition including the organometallic compound

ABSTRACT

An organometallic compound represented by Formula 1: 
     
       
         
         
             
             
         
       
         
         
           
             wherein, in Formula 1, groups and variables are the same as described in the specification.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Applications Nos.10-2018-0104028, filed on Aug. 31, 2018, and 10-2019-0104976, filed onAug. 27, 2019, in the Korean Intellectual Property Office, and all thebenefits accruing therefrom under 35 U.S.C. § 119, the contents of whichare incorporated herein in their entirety by reference.

BACKGROUND 1. Field

An embodiment relates to an organometallic compound, an organiclight-emitting device including the same, and a diagnostic compositionincluding the organometallic compound.

2. Description of the Related Art

Organic light-emitting devices (OLEDs) are self-emission devices, whichhave superior characteristics in terms of a viewing angle, a responsetime, a brightness, a driving voltage, and a response speed, and whichproduce full-color images.

In an example, an organic light-emitting device includes an anode, acathode, and an organic layer disposed between the anode and thecathode, wherein the organic layer includes an emission layer. A holetransport region may be disposed between the anode and the emissionlayer, and an electron transport region may be disposed between theemission layer and the cathode. Holes provided from the anode may movetoward the emission layer through the hole transport region, andelectrons provided from the cathode may move toward the emission layerthrough the electron transport region. The holes and the electronsrecombine in the emission layer to produce excitons. These excitonstransit from an excited state to a ground state, thereby generatinglight.

Meanwhile, luminescent compounds may be used to monitor, sense, ordetect a variety of biological materials including cells and proteins.An example of the luminescent compounds includes a phosphorescentluminescent compound.

Various types of organic light emitting devices are known. However,there still remains a need in OLEDs having low driving voltage, highefficiency, high brightness, and long lifespan.

SUMMARY

Aspects of the present disclosure provide an organometallic compound, anorganic light-emitting device including the same, and a diagnosticcomposition including the organometallic compound.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

An aspect of the present disclosure provides an organometallic compoundrepresented by Formula 1:

In Formula 1,

-   -   M may be a transition metal,    -   X₁ may be O or S, wherein a bond between X₁ and M may be a        covalent bond,    -   X₂ to X₄ may each independently be C or N,    -   a bond between X₂ and M, a bond between X₃ and M, or a bond        between X₄ and M may be a covalent bond, and the other bonds of        a bond between X₂ and M, a bond between X₃ and M, or a bond        between X₄ and M may be coordinate bonds,    -   Y₁ and Y₃ to Y₅ may each independently be C or N,    -   a bond between X₂ and Y₃, a bond between X₂ and Y₄, and a bond        between Y₄ and Y₅ may be a chemical bond, ring CY₁ to ring CY₄        and ring CY₅₁ may each independently be a C₅-C₃₀ carbocyclic        group or a C₂-C₃₀ heterocyclic group,    -   a cyclometalated ring formed by ring CY₅, ring CY₂, ring CY₃,        and M may be a 6-membered ring,    -   T₁ may be a single bond, a double bond, *—N(R₅)—*′, *—B(R₅)—*′,        *—P(R₅)—*′, *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′, *—Ge(R₅)(R₆)—*′,        *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′,        *—C(R₅)=*′, *═C(R₅)—*′, *—C(R₅)═C(R₆)—*′, *—C(═S)—*′, or        *—C≡C—*′, wherein * and *′ each indicate a binding site to a        neighboring atom,    -   L₁ to L₄ and L₅₁ may each independently be a single bond, a        C₅-C₃₀ carbocyclic group that is unsubstituted or substituted        with an R_(10a) group, or a C₂-C₃₀ heterocyclic group that is        unsubstituted or substituted with an R_(10a) group,    -   b1 to b4 and b51 may each independently be an integer from 1 to        5,    -   R₁ to R₆, R₅₁, and R₅₂ may each independently be hydrogen,        deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano        group, a nitro group, an amidino group, a hydrazine group, a        hydrazone group, a carboxylic acid group or a salt thereof, a        sulfonic acid group or a salt thereof, a phosphoric acid group        or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkyl        group, a substituted or unsubstituted C₂-C₆₀ alkenyl group, a        substituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted        or unsubstituted C₁-C₆₀ alkoxy group, a substituted or        unsubstituted C₃-C₁₀ cycloalkyl group, a substituted or        unsubstituted C₂-C₁₀ heterocycloalkyl group, a substituted or        unsubstituted C₃-C₁₀ cycloalkenyl group, a substituted or        unsubstituted C₂-C₁₀ heterocycloalkenyl group, a substituted or        unsubstituted C₆-C₆₀ aryl group, a substituted or unsubstituted        C₆-C₆₀ aryloxy group, a substituted or unsubstituted C₆-C₆₀        arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkyl        group, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, a        substituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a        substituted or unsubstituted C₁-C₆₀ heteroarylthio group, a        substituted or unsubstituted C₂-C₆₀ heteroarylalkyl group, a        substituted or unsubstituted monovalent non-aromatic condensed        polycyclic group, a substituted or unsubstituted monovalent        non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂),        —Si(Q₃)(Q₄)(Q₅), —Ge(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), —P(═O)(Q₈)(Q₉), or        —P(Q₈)(Q₉),    -   c1 to c4, c51, and c52 may each independently be an integer from        1 to 5,    -   A₅₁ may be a C₄-C₆₀ alkyl group,    -   A₅₂ may be deuterium or a deuterium-containing C₁-C₆₀ alkyl        group unsubstituted or substituted with a C₃-C₁₀ cycloalkyl        group,    -   a1 to a4, a51, and a52 may each independently be an integer from        0 to 10, provided that the sum of a51 and a52 may be 1 or more,    -   a53 may be an integer from 1 to 10,    -   two or more groups of a plurality of R₁ groups may optionally be        linked to form a C₅-C₃₀ carbocyclic group that is unsubstituted        or substituted with an R_(10a) group or a C₂-C₃₀ heterocyclic        group that is unsubstituted or substituted with an R_(10a)        group,    -   two or more groups of a plurality of R₂ groups may optionally be        linked to form a C₅-C₃₀ carbocyclic group that is unsubstituted        or substituted with an R_(10a) group or a C₂-C₃₀ heterocyclic        group that is unsubstituted or substituted with an R_(10a)        group,    -   two or more groups of a plurality of R₃ groups may optionally be        linked to form a C₅-C₃₀ carbocyclic group that is unsubstituted        or substituted with an R_(10a) group or a C₂-C₃₀ heterocyclic        group that is unsubstituted or substituted with an R_(10a)        group,    -   two or more groups of a plurality of R₄ groups may optionally be        linked to form a C₅-C₃₀ carbocyclic group that is unsubstituted        or substituted with an R_(10a) group or a C₂-C₃₀ heterocyclic        group that is unsubstituted or substituted with an R_(10a)        group,    -   two or more groups of R₁ to R₆ may optionally be linked to form        a C₅-C₃₀ carbocyclic group that is unsubstituted or substituted        with an R_(10a) group or a C₂-C₃₀ heterocyclic group that is        unsubstituted or substituted with an R_(10a) group,    -   R_(10a) may be the same as described in connection with R₁,    -   a substituent of the substituted C₁-C₆₀ alkyl group, the        substituted C₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl        group, the substituted C₁-C₆₀ alkoxy group, the substituted        C₃-C₁₀ cycloalkyl group, the substituted C₂-C₁₀ heterocycloalkyl        group, the substituted C₃-C₁₀ cycloalkenyl group, the        substituted C₂-C₁₀ heterocycloalkenyl group, the substituted        C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxy group, the        substituted C₆-C₆₀ arylthio group, the substituted C₇-C₆₀        arylalkyl group, the substituted C₁-C₆₀ heteroaryl group, the        substituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀        heteroaryl group, the substituted C₁-C₆₀ heteroaryloxy group,        the substituted C₁-C₆₀ heteroarylthio group, the substituted        C₂-C₆₀ heteroarylalkyl group, the substituted monovalent        non-aromatic condensed polycyclic group, and the substituted        monovalent non-aromatic condensed heteropolycyclic group is:    -   a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,        —CFH₂, a hydroxyl group, a cyano group, a nitro group, an        amidino group, a hydrazine group, a hydrazone group, a        carboxylic acid group or a salt thereof, a sulfonic acid group        or a salt thereof, a phosphoric acid group or a salt thereof, a        C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl        group, or a C₁-C₆₀ alkoxy group;    -   a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl        group, or a C₁-C₆₀ alkoxy group, each substituted with        deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H,        —CFH₂, a hydroxyl group, a cyano group, a nitro group, an        amidino group, a hydrazine group, a hydrazone group, a        carboxylic acid group or a salt thereof, a sulfonic acid group        or a salt thereof, a phosphoric acid group or a salt thereof, a        C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a        C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a        C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio        group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a        C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a        C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic        condensed polycyclic group, a monovalent non-aromatic condensed        heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),        —Ge(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), —P(═O)(Q₁₈)(Q₁₉),        —P(Q₁₈)(Q₁₉), or any combination thereof;    -   a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a        C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a        C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio        group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroaryl group, a        C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, a        C₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic        condensed polycyclic group, and a monovalent non-aromatic        condensed heteropolycyclic group, each unsubstituted or        substituted with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,        —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a        nitro group, an amidino group, a hydrazine group, a hydrazone        group, a carboxylic acid group or a salt thereof, a sulfonic        acid group or a salt thereof, a phosphoric acid group or a salt        thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀        alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀ cycloalkyl group,        a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a        C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀        aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl        group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group,        a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a        monovalent non-aromatic condensed polycyclic group, a monovalent        non-aromatic condensed heteropolycyclic group, —N(Q₂₁)(Q₂₂),        —Si(Q₂₃)(Q₂₄)(Q₂₅), —Ge(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇),        —P(═O)(Q₂₈)(Q₂₉), —P(Q₂₈)(Q₂₉), or any combination thereof;    -   —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —Ge(Q₃₃)(Q₃₄)(Q₃₅),        —B(Q₃₆)(Q₃₇), —P(═O)(Q₃₈)(Q₃₉), or —P(Q₃₈)(Q₃₉); or    -   any combination thereof; and    -   Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ are each        independently hydrogen; deuterium; —F; —Cl; —Br; —I; a hydroxyl        group; a cyano group; a nitro group; an amidino group; a        hydrazine group; a hydrazone group; a carboxylic acid group or a        salt thereof; a sulfonic acid group or a salt thereof; a        phosphoric acid group or a salt thereof; a C₁-C₆₀ alkyl group        unsubstituted or substituted with deuterium, a C₁-C₆₀ alkyl        group, a C₆-C₆₀ aryl group, or any combination thereof; a C₂-C₆₀        alkenyl group; a C₂-C₆₀ alkynyl group; a C₁-C₆₀ alkoxy group; a        C₃-C₁₀ cycloalkyl group; a C₂-C₁₀ heterocycloalkyl group; a        C₃-C₁₀ cycloalkenyl group; a C₂-C₁₀ heterocycloalkenyl group; a        C₆-C₆₀ aryl group unsubstituted or substituted with deuterium, a        C₁-C₆₀ alkyl group, a C₆-C₆₀ aryl group, or any combination        thereof; a C₆-C₆₀ aryloxy group; a C₆-C₆₀ arylthio group; a        C₇-C₆₀ arylalkyl group; a C₁-C₆₀ heteroaryl group; a C₁-C₆₀        heteroaryloxy group; a C₁-C₆₀ heteroarylthio group; a C₂-C₆₀        heteroarylalkyl group; a monovalent non-aromatic condensed        polycyclic group; or a monovalent non-aromatic condensed        heteropolycyclic group.

Another aspect of the present disclosure provides an organiclight-emitting device including:

-   -   a first electrode;    -   a second electrode; and    -   an organic layer disposed between the first electrode and the        second electrode,    -   wherein the organic layer includes an emission layer and an        organometallic compound represented by Formula 1.

The organometallic compound included in the emission layer in theorganic layer may act as a dopant.

Another aspect of the present disclosure provides a diagnosticcomposition including an organometallic compound represented by Formula1.

BRIEF DESCRIPTION OF THE DRAWING

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the FIGURE which is a schematic view of an organiclight-emitting device according to an embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items. Expressions such as “at least one of,” whenpreceding a list of elements, modify the entire list of elements and donot modify the individual elements of the list.

It will be understood that when an element is referred to as being “on”another element, it can be directly in contact with the other element orintervening elements may be present therebetween. In contrast, when anelement is referred to as being “directly on” another element, there areno intervening elements present.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers, and/or sections, these elements, components, regions, layers,and/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer, orsection from another element, component, region, layer, or section.Thus, a first element, component, region, layer, or section discussedbelow could be termed a second element, component, region, layer, orsection without departing from the teachings of the present embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise.

The term “or” means “and/or.” It will be further understood that theterms “comprises” and/or “comprising,” or “includes” and/or “including”when used in this specification, specify the presence of statedfeatures, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this general inventive conceptbelongs. It will be further understood that terms, such as those definedin commonly used dictionaries, should be interpreted as having a meaningthat is consistent with their meaning in the context of the relevant artand the present disclosure, and will not be interpreted in an idealizedor overly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

In an embodiment, an organometallic compound is provided. Theorganometallic compound according to an embodiment may be represented byFormula 1:

In Formula 1, M may be a transition metal. Alternatively, M may beberyllium (Be), magnesium (Mg), aluminum (Al), calcium (Ca), titanium(Ti), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), gallium (Ga),germanium (Ge), zirconium (Zr), ruthenium (Ru), rhodium (Rh), palladium(Pd), silver (Ag), rhenium (Re), platinum (Pt), or gold (Au). Forexample, M may be Pt, Pd, or Au.

In Formula 1, X₁ may be O or S, wherein a bond between X₁ and M may be acovalent bond. For example, X₁ may be O.

In Formula 1, X₂ to X₄ may each independently be C or N. For example, X₂and X₃ may each independently be C or N, and X₄ may be N.

In an embodiment, in Formula 1, X₂ and X₄ may each be N, and X₃ may beC, but embodiments of the present disclosure are not limited thereto.

In Formula 1, a bond between X₂ and M, a bond between X₃ and M, or abond between X₄ and M may be a covalent bond, and the other bonds of abond between X₂ and M, a bond between X₃ and M, and a bond between X₄and M may be coordinate bonds. Therefore, the organometallic compoundrepresented by Formula 1 may be electrically neutral.

In an embodiment, a bond between X₂ and M and a bond between X₄ and Mmay be a coordinate bond, and a bond between X₃ and M may be a covalentbond, but embodiments of the present disclosure are not limited thereto.

In Formula 1, Y₁ and Y₃ to Y₅ may each independently be C or N. Forexample, Y₁ and Y₃ to Y₅ may be C.

In Formula 1, a bond between X₂ and Y₃, a bond between X₂ and Y₄, and abond between Y₄ and Y₅ may be a chemical bond (for example, a singlebond, a double bond, or the like).

In Formula 1, ring CY₁ to ring CY₄ and ring CY₅₁ may each independentlybe a C₅-C₃₀ carbocyclic group or a C₂-C₃₀ heterocyclic group.

For example, ring CY₁ to ring CY₄ and ring CY₅₁ may each independentlybe i) a first ring, ii) a second ring, iii) a condensed ring in which atleast two first rings are condensed, iv) a condensed ring in which atleast two second rings are condensed, or v) a condensed ring in which afirst ring and a second ring are condensed.

In an embodiment, the first ring may be a cyclopentane group, acyclopentadiene group, a furan group, a thiophene group, a pyrrolegroup, a silole group, an indene group, a benzofuran group, abenzothiophene group, an indole group, a benzosilole group, an oxazolegroup, an isoxazole group, an oxadiazole group, an isoxadiazole group,an oxatriazole group, an isoxatriazole group, a thiazole group, anisothiazole group, a thiadiazole group, an isothiadiazole group, athiatriazole group, an isothiatriazole group, a pyrazole group, animidazole group, a triazole group, a tetrazole group, an azasilolegroup, a diazasilole group, or a triazasilole group, and the second ringmay be an adamantane group, a norbornene group, a bicyclo[1.1.1]pentanegroup, a bicyclo[2.1.1]hexane group, a bicyclo[2.2.1]heptane group, abicyclo[2.2.2]octane group, a cyclohexane group, a cyclohexene group, abenzene group, a pyridine group, a pyrimidine group, a pyrazine group, apyridazine group, or a triazine group.

In an embodiment, in Formula 1, ring CY₁ to ring CY₄ and ring CY₅₁ mayeach independently be a cyclopentane group, a cyclohexane group, acycloheptane group, a cyclopentene group, a cyclohexene group, acycloheptene group, a benzene group, a naphthalene group, an anthracenegroup, a phenanthrene group, a triphenylene group, a pyrene group, achrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalenegroup, a thiophene group, a furan group, an indole group, a benzoborolegroup, a benzophosphole group, an indene group, a benzosilole group, abenzogermole group, a benzothiophene group, a benzoselenophene group, abenzofuran group, a carbazole group, a dibenzoborole group, adibenzophosphole group, a fluorene group, a dibenzosilole group, adibenzogermole group, a dibenzothiophene group, a dibenzoselenophenegroup, a dibenzofuran group, a dibenzothiophene 5-oxide group, a9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, anazaindole group, an azabenzoborole group, an azabenzophosphole group, anazaindene group, an azabenzosilole group, an azabenzogermole group, anazabenzothiophene group, an azabenzoselenophene group, an azabenzofurangroup, an azacarbazole group, an azadibenzoborole group, anazadibenzophosphole group, an azafluorene group, an azadibenzosilolegroup, an azadibenzogermole group, an azadibenzothiophene group, anazadibenzoselenophene group, an azadibenzofuran group, anazadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, anazadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidinegroup, a pyrazine group, a pyridazine group, a triazine group, aquinoline group, an isoquinoline group, a quinoxaline group, aquinazoline group, a phenanthroline group, a pyrrole group, a pyrazolegroup, an imidazole group, a triazole group, an oxazole group, anisoxazole group, a thiazole group, an isothiazole group, an oxadiazolegroup, a thiadiazole group, a benzopyrazole group, a benzimidazolegroup, a benzoxazole group, a benzothiazole group, a benzoxadiazolegroup, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group,or a 5,6,7,8-tetrahydroquinoline group.

In an embodiment, in Formula 1, ring CY₄ may not be a benzimidazolegroup.

In Formula 1, a cyclometalated ring formed by ring CY₅, ring CY₂, ringCY₃, and M may be a 6-membered ring.

In Formula 1, T₁ may be a single bond, a double bond, *—N(R₅)—*′,*—B(R₅)—*′, *—P(R₅)—*′, *—C(R₅)(R₆)—*′, *—Si(R₅)(R₆)—*′,*—Ge(R₅)(R₆)—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′,*—S(═O)₂—*′, *—C(R₅)=*′, *═C(R₅)—*′, *—C(R₅)═C(R₆)—*′, *—C(═S)-, or*—C≡C—*′, wherein * and *′ each indicate a binding site to a neighboringatom. Here, R₅ and R₆ are the same as described above, and mayoptionally be linked to each other via a single bond, a double bond,*—N(R′)—*′, *—B(R′)—*′, *—P(R′)—*′, *—C(R′)(R″)—*′, *—Si(R′)(R″)—*′,*—Ge(R′)(R″)—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′,*—S(═O)₂—*′, *—C(R′)=*′ *═C(R′)—*′, *—C(R′)═C(R″)—*′, *—C(═S)—*′, or*—C≡C—*′ to form a C₅-C₃₀ carbocyclic group that is unsubstituted orsubstituted with an R_(10a) group or a C₂-C₃₀ heterocyclic group that isunsubstituted or substituted with an R_(10a) group. R′, R″, and R_(10a)are each independently defined the same as R₁.

For example, in Formula 1, T₁ may be a single bond, but embodiments ofthe present disclosure are not limited thereto.

In Formula 1, L₁ to L₄ and L₅₁ may each independently be a single bond,a C₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group, or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group. Here, R_(10a) is defined the same asR₁.

For example, in Formula 1, L₁ to L₄ and L₅₁ may each independently be:

-   -   a single bond; or    -   a benzene group, a naphthalene group, an anthracene group, a        phenanthrene group, a triphenylene group, a pyrene group, a        chrysene group, a cyclopentadiene group, a furan group, a        thiophene group, a silole group, an indene group, a fluorene        group, an indole group, a carbazole group, a benzofuran group, a        dibenzofuran group, a benzothiophene group, a dibenzothiophene        group, a benzosilole group, a dibenzosilole group, an        azafluorene group, an azacarbazole group, an azadibenzofuran        group, an azadibenzothiophene group, an azadibenzosilole group,        a pyridine group, a pyrimidine group, a pyrazine group, a        pyridazine group, a triazine group, a quinoline group, an        isoquinoline group, a quinoxaline group, a quinazoline group, a        phenanthroline group, a pyrrole group, a pyrazole group, an        imidazole group, a triazole group, an oxazole group, an        isoxazole group, a thiazole group, an isothiazole group, an        oxadiazole group, a thiadiazole group, a benzopyrazole group, a        benzimidazole group, a benzoxazole group, a benzothiazole group,        a benzoxadiazole group, or a benzothiadiazole group, each        unsubstituted or substituted with an R_(10a) group.

In an embodiment, in Formula 1, L₁ to L₄ and L₅₁ may each independentlybe:

-   -   a single bond; or    -   a benzene group unsubstituted or substituted with an R_(10a)        group,    -   but embodiments of the present disclosure are not limited        thereto.

In an embodiment, in Formula 1,

Y₁ and X₃ may be C, and X₂ and X₄ may be N,

ring CY₁ to ring CY₃ and ring CY₅₁ may be a benzene group, and ring CY₄may be a pyridine group, and

L₄ and L₅₁ may each independently be:

-   -   a single bond; or    -   a benzene group unsubstituted or substituted with an R_(10a)        group.

In Formula 1, b1 to b4 and b51 each indicate the number of L₁ to L₄ andL₅₁, respectively, and may each independently be an integer from 1 to 5.When b1 is two or more, two or more L₁ groups may be identical to ordifferent from each other, when b2 is two or more, two or more L₂ groupsmay be identical to or different from each other, when b3 is two ormore, two or more L₃ groups may be identical to or different from eachother, when b4 is two or more, two or more L₄ groups may be identical toor different from each other, and when b51 is two or more, two or moreL₅₁ groups may be identical to or different from each other.

For example, in Formula 1, b1 to b4 and b51 may each independently be 1,2 or 3, but embodiments of the present disclosure are not limitedthereto.

In Formula 1, R₁ to R₆, R₅₁, and R₅₂ may each independently be hydrogen,deuterium, —F, —Cl, —Br, —I, —SF₅, a hydroxyl group, a cyano group, anitro group, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a substituted orunsubstituted C₁-C₆₀ alkyl group, a substituted or unsubstituted C₂-C₆₀alkenyl group, a substituted or unsubstituted C₂-C₆₀ alkynyl group, asubstituted or unsubstituted C₁-C₆₀ alkoxy group, a substituted orunsubstituted C₃-C₁₀ cycloalkyl group, a substituted or unsubstitutedC₂-C₁₀ heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted C₂-C₁₀heterocycloalkenyl group, a substituted or unsubstituted C₆-C₆₀ arylgroup, a substituted or unsubstituted C₆-C₆₀ aryloxy group, asubstituted or unsubstituted C₆-C₆₀ arylthio group, a substituted orunsubstituted C₇-C₆₀ arylalkyl group, a substituted or unsubstitutedC₁-C₆₀ heteroaryl group, a substituted or unsubstituted C₁-C₆₀heteroaryloxy group, a substituted or unsubstituted C₁-C₆₀heteroarylthio group, a substituted or unsubstituted C₂-C₆₀heteroarylalkyl group, a substituted or unsubstituted monovalentnon-aromatic condensed polycyclic group, a substituted or unsubstitutedmonovalent non-aromatic condensed heteropolycyclic group, —N(Q₁)(Q₂),—Si(Q₃)(Q₄)(Q₅), —Ge(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), —P(═O)(Q₈)(Q₉), or—P(Q₈)(Q₉), wherein Q₁ to Q₉ are each independently the same asdescribed above.

For example, R₁ to R₆, R₅₁, and R₅₂ may each independently be:

-   -   a hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a        cyano group, a nitro group, an amino group, an amidino group, a        hydrazine group, a hydrazone group, a carboxylic acid group or a        salt thereof, a sulfonic acid group or a salt thereof, a        phosphoric acid group or a salt thereof, —SF₅, C₁-C₂₀ alkyl        group, or a C₁-C₂₀ alkoxy group;    -   a C₁-C₂₀ alkyl group and a C₁-C₂₀ alkoxy group, each substituted        with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,        —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an        amino group, an amidino group, a hydrazine group, a hydrazone        group, a carboxylic acid group or a salt thereof, a sulfonic        acid group or a salt thereof, a phosphoric acid group or a salt        thereof, a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexyl        group, a cycloheptyl group, a cyclooctyl group, an adamantyl        (adamantyl) group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, a        naphthyl group, a pyridinyl group, a pyrimidinyl group, or any        combination thereof;    -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclooctyl group, an adamantyl group, a norbornenyl group, a        cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl        group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl        group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl        group, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl        group, a terphenyl group, a naphthyl group, a fluorenyl group, a        phenanthrenyl group, an anthracenyl group, a fluoranthenyl        group, a triphenylenyl group, a pyrenyl group, a chrysenyl        group, a pyrrolyl group, a thiophenyl group, a furanyl group, an        imidazolyl group, a pyrazolyl group, a thiazolyl group, an        isothiazolyl group, an oxazolyl group, an isoxazolyl group, a        pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a        pyridazinyl group, an isoindolyl group, an indolyl group, an        indazolyl group, a purinyl group, a quinolinyl group, an        isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl        group, a quinazolinyl group, a cinnolinyl group, a carbazolyl        group, a phenanthrolinyl group, a benzimidazolyl group, a        benzofuranyl group, a benzothiophenyl group, an        isobenzothiazolyl group, a benzoxazolyl group, an        isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an        oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a        dibenzothiophenyl group, a benzocarbazolyl group, a        dibenzocarbazolyl group, an imidazopyridinyl group, an        imidazopyrimidinyl group, an azacarbazolyl group, an        azadibenzofuranyl group, or an azadibenzothiophenyl group, each        unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I,        —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a        cyano group, a nitro group, an amino group, an amidino group, a        hydrazine group, a hydrazone group, a carboxylic acid group or a        salt thereof, a sulfonic acid group or a salt thereof, a        phosphoric acid group or a salt thereof, a C₁-C₂₀ alkyl group, a        deuterium-containing C₂-C₂₀ alkyl group (for example,        *—C(CD₃)₃), a C₁-C₂₀ alkoxy group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, a        naphthyl group, a fluorenyl group, a phenanthrenyl group, an        anthracenyl group, a fluoranthenyl group, a triphenylenyl group,        a pyrenyl group, a chrysenyl group, a pyrrolyl group, a        thiophenyl group, a furanyl group, an imidazolyl group, a        pyrazolyl group, a thiazolyl group, an isothiazolyl group, an        oxazolyl group, an isoxazolyl group, a pyridinyl group, a        pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an        isoindolyl group, an indolyl group, an indazolyl group, a        purinyl group, a quinolinyl group, an isoquinolinyl group, a        benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl        group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl        group, a benzimidazolyl group, a benzofuranyl group, a        benzothiophenyl group, an isobenzothiazolyl group, a        benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group,        a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a        dibenzofuranyl group, a dibenzothiophenyl group, a        benzocarbazolyl group, a dibenzocarbazolyl group, an        imidazopyridinyl group, an imidazopyrimidinyl group, an        azacarbazolyl group, an azadibenzofuranyl group, an        azadibenzothiophenyl group, or any combination thereof; or    -   —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —Ge(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇),        —P(═O)(Q₈)(Q₉), or —P(Q₈)(Q₉), and    -   Q₁ to Q₉ may each independently be:    -   —CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂,        —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, or        —CD₂CDH₂; or    -   an n-propyl group, an iso-propyl group, an n-butyl group, a        sec-butyl group, an iso-butyl group, a tert-butyl group, an        n-pentyl group, a tert-pentyl group, a neo-pentyl group, an        iso-pentyl group, a sec-pentyl group, a 3-pentyl group, a        sec-iso-pentyl group, a phenyl group, a biphenyl group or a        naphthyl group, each unsubstituted or substituted with        deuterium, a C₁-C₁₀ alkyl group, a phenyl group, or any        combination thereof,    -   but embodiments of the present disclosure are not limited        thereto.

In Formula 1, c1 to c4, c51, and c52 each indicate the number of R₁ toR₄, R₅₁, and R₅₂, respectively, and may each independently be an integerfrom 1 to 5. When c1 is two or more, two or more R₁ groups may beidentical to or different from each other, when c2 is two or more, twoor more R₂ groups may be identical to or different from each other, whenc3 is two or more, two or more R₃ groups may be identical to ordifferent from each other, when c4 is two or more, two or more R₄ groupsmay be identical to or different from each other, when c51 is two ormore, two or more R₅₁ groups may be identical to or different from eachother, and when c52 is two or more, two or more R₅₂ groups may beidentical to or different from each other. For example, c1 to c4, c51,and c52 may each independently be 1 or 2, but embodiments of the presentdisclosure are not limited thereto.

In Formula 1, A₅₁ may be a C₄-C₆₀ alkyl group, and A₅₂ may be deuteriumor a deuterium-containing C₁-C₆₀ alkyl group unsubstituted orsubstituted with a C₃-C₁₀ cycloalkyl group.

In an embodiment, in Formula 1, A₅₁ may be a linear or branched C₄-C₁₀alkyl group, and A₅₂ may be deuterium or a deuterium-containing linearor branched C₁-C₂₀ alkyl group unsubstituted or substituted with aC₃-C₁₀ cycloalkyl group.

In an embodiment, in Formula 1, A₅₁ may be an n-butyl group, a sec-butylgroup, an iso-butyl group, a tert-butyl group, an n-pentyl group, atert-pentyl group, a neo-pentyl group, an iso-pentyl group, a sec-pentylgroup, a 3-pentyl group, or a sec-iso-pentyl group, unsubstituted orsubstituted with a methyl group, an ethyl group, an n-propyl group, aniso-propyl group, an n-butyl group, a sec-butyl group, an iso-butylgroup, a tert-butyl group, an n-pentyl group, a tert-pentyl group, aneo-pentyl group, an iso-pentyl group, a sec-pentyl group, a 3-pentylgroup, a sec-iso-pentyl group, or any combination thereof. For example,Formula 9-33 may be a branched C₆ alkyl group and a tert-butyl groupsubstituted with two methyl groups.

In an embodiment, in Formula 1, A₅₂ may be a deuterium-containing linearor branched C₁-C₂₀ alkyl group unsubstituted or substituted with aC₃-C₁₀ cycloalkyl group, in which the linear or branched C₁-C₂₀ alkylgroup may be a methyl group, an ethyl group, an n-propyl group, aniso-propyl group, an n-butyl group, a sec-butyl group, an iso-butylgroup, a tert-butyl group, an n-pentyl group, a tert-pentyl group, aneo-pentyl group, an iso-pentyl group, a sec-pentyl group, a 3-pentylgroup, or a sec-iso-pentyl group, unsubstituted or substituted with amethyl group, an ethyl group, an n-propyl group, an iso-propyl group, ann-butyl group, a sec-butyl group, an iso-butyl group, a tert-butylgroup, an n-pentyl group, a tert-pentyl group, a neo-pentyl group, aniso-pentyl group, a sec-pentyl group, a 3-pentyl group, a sec-iso-pentylgroup, or any combination thereof.

The deuterium-containing C₁-C₆₀ alkyl group (or, thedeuterium-containing C₁-C₂₀ alkyl group, the deuterium-containing C₂-C₂₀alkyl group, etc.) means a C₁-C₆₀ alkyl group substituted with adeuterium (or, a C₁-C₂₀ alkyl group substituted with a deuterium, aC₂-C₂₀ alkyl group substituted with a deuterium, etc.). For example, adeuterium-containing C₁ alkyl group (that is, a deuterium-containingmethyl group) includes —CD₃, —CD₂H and —CDH₂.

The deuterium-containing C₁-C₆₀ alkyl group (or, thedeuterium-containing C₁-C₂₀ alkyl group, the deuterium-containing C₂-C₂₀alkyl group, etc.) may be additionally substituted with a C₃-C₁₀cycloalkyl group. For example, Formula 9-619 is a group corresponding to—CD₂H, in which “—H” is substituted with a cyclopentyl group.

The organometallic compound represented by Formula 1 may include adeuterium, a deuterium-containing C₁-C₆₀ alkyl group unsubstituted orsubstituted with a C₃-C₁₀ cycloalkyl group, or any combination thereof.The number of deuterium atoms in the organometallic compound representedby Formula 1 may be from 1 to 20, for example, from 1 to 15, from 1 to10, or from 1 to 5.

In an embodiment, regarding Formula 1,

-   -   R₁ to R₆, R₅₁, and R₅₂ may each independently be:    -   hydrogen, deuterium, —F, a cyano group, a nitro group, —SF₅,        —CH₃, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a group        represented by one of Formulae 9-1 to 9-66, a group represented        by one of Formulae 9-1 to 9-66 in which a hydrogen is        substituted with deuterium, a group represented by one of        Formulae 10-1 to 10-118, a group represented by one of Formulae        10-1 to 10-118 in which a hydrogen is substituted with        deuterium, a group represented by one of Formulae 10-201 to        10-342, or a group represented by one of Formulae 10-201 to        10-342 in which a hydrogen is substituted with deuterium, and/or    -   A₅₁ may be a group represented by one of Formulae 9-4 to 9-36,        and/or    -   A₅₂ may be a group represented by one of Formulae 9-1 to 9-63 in        which a hydrogen is substituted with deuterium, and/or    -   a group represented by

in Formula 1 may be a group represented by one of Formulae 10-10 to10-118, or a group represented by one of Formulae 10-10 to 10-118 inwhich a hydrogen is substituted with deuterium:

In Formulae 9-1 to 9-66, 10-1 to 10-118 and 10-201 to 10-342, *indicates a binding site to a neighboring atom, Ph indicates a phenylgroup, and TMS indicates a trimethylsilyl group.

The “group represented by one of Formulae 9-1 to 9-66 in which ahydrogen is substituted with deuterium” may be, for example, a grouprepresented by one of Formulae 9-501 to 9-514 or 9-601 to 9-638.

The “group represented by one of Formulae 10-1 to 10-118 in which ahydrogen is substituted with deuterium” may be, for example, a grouprepresented by one of Formulae 10-501 to 10-552:

In an embodiment, in Formula 1, A₅₂ may be a group represented by one ofFormulae 9-1 to 9-36 in which all hydrogens are substituted withdeuterium, but embodiments of the present disclosure are not limitedthereto.

In Formula 1, a1 to a4, a51, and a52 each indicate the number of*-[(L₁)_(b1)-(R₁)_(c1)], *-[(L₂)_(b2)-(R₂)_(c2)],*-[(L₃)_(b3)-(R₃)_(c3)], *-[(L₄)_(b4)-(R₄)_(c4)], A₅₁, and A₅₂,respectively, and may each independently be an integer from 0 to 10.When a1 is two or more, two or more *-[(L₁)_(b1)-(R₁)_(c1)] groups maybe identical to or different from each other, when a2 is two or more,two or more *-[(L₂)_(b2)-(R₂)_(c2)] groups may be identical to ordifferent from each other, when a3 is two or more, two or more*-[(L₃)_(b3)-(R₃)_(c3)] groups may be identical to or different fromeach other, when a4 is two or more, two or more *-[(L₄)_(b4)-(R₄)_(c4)]groups may be identical to or different from each other, when a51 is twoor more, two or more A₅₁ groups may be identical to or different fromeach other, and when a52 is two or more, two or more A₅₂ groups may beidentical to or different from each other, but embodiments of thepresent disclosure are not limited thereto.

For example, in Formula 1, a1 to a4, a51, and a52 may each independentlybe 0, 1, 2, 3, 4, 5, or 6, but embodiments of the present disclosure arenot limited thereto.

For example, in Formula 1, a1 and a4 may each independently be 0, 1, 2,3, or 4 and a2, a3, a51 and a52 may each independently be 0, 1, 2, or 3.

In Formula 1, the sum of a51 and a52 may be 1 or more. That is, inFormula 1, ring CY₅₁ may be substituted with a group represented by A₅₁,a group represented by A₅₂, or any combination thereof.

For example, the sum of a51 and a52 may be 1, 2, or 3. In an embodiment,the sum of a51 and a52 may be 1 or 2.

In Formula 1, a53 indicates the number of groups represented by

and may be an integer from 1 to 10. Since a53 in Formula 1 is not 0,ring CY₅₁ in

Formula 1 is substituted with a group represented by

In an embodiment, in Formula 1,

-   -   L₁ to L₃ may be a single bond, and    -   R₁ to R₃ may each independently be:    -   hydrogen, deuterium, —F, a cyano group, C₁-C₂₀ alkyl group, or a        C₁-C₂₀ alkoxy group;    -   a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₁₀ alkyl group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof; or    -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclooctyl group, an adamantyl group, a norbornenyl group, a        cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl        group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl        group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl        group, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl        group, or a terphenyl group, each unsubstituted or substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀        alkyl group (for example, *—C(CD₃)₃), a C₁-C₂₀ alkoxy group, a        cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclooctyl group, an adamantyl group, a norbornenyl group, a        cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl        group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl        group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl        group, a (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀        alkyl)cyclohexyl group, a (C₁-C₂₀ alkyl)cycloheptyl group, a        (C₁-C₂₀ alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group,        a (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.

In an embodiment, in Formula 1, a3, and a4 may not be 0, and a grouprepresented by *-(L₃)_(b3)-(R₃)_(c3), and a group represented by*-(L₄)_(b4)-(R₄)_(c4) may not be hydrogen.

In an embodiment, in Formula 1, a1, a3, and a4 may not be 0, and a grouprepresented by *-(L₁)_(b1)-(R₁)_(c1), a group represented by*-(L₃)_(b3)-(R₃)_(c3), and a group represented by *-(L₄)_(b4)-(R₄)_(c4)may not be hydrogen.

In an embodiment, in Formula 1, a1 may not be 0, a group represented by*-(L₁)_(b1)-(R₁)_(c1) may not be hydrogen, and a group represented by*-(L₁)_(b1)-(R₁)_(c1) in a number of a1 may include a deuterium.

In an embodiment, in Formula 1, a1 may be 2, two groups represented by*-(L₁)_(b1)-(R₁)_(c1) may not be hydrogen, and two groups represented by*-(L₁)_(b1)-(R₁)_(c1) may be identical to each other.

In an embodiment, in Formula 1, a1 may be 2, two groups represented by*-(L₁)_(b1)-(R₁)_(c1) may not be hydrogen, and two groups represented by*-(L₁)_(b1)-(R₁)_(c1) may be different from each other.

In an embodiment, in Formula 1, a4 may not be 0, a group represented by*-(L₄)_(b4)-(R₄)_(c4) may not be hydrogen, and a group represented by*-(L₄)_(b4)-(R₄)_(c4) in a number of a4 may include a deuterium.

In an embodiment, in Formula 1, a3 may not be 0, and a group representedby *-(L₃)_(b3)-(R₃)_(c3) in a number of a3 may satisfy Condition A andCondition B:

-   -   Condition A    -   L₃ is a single bond.    -   Condition B    -   R₃ is    -   hydrogen, deuterium, —F, a cyano group, C₁-C₂₀ alkyl group, or a        C₁-C₂₀ alkoxy group;    -   a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₁₀ alkyl group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof; or    -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclooctyl group, an adamantyl group, a norbornenyl group, a        cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl        group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl        group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl        group, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl        group, or a terphenyl group, each unsubstituted or substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀        alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.

In an embodiment, in Condition B, R₃ may not hydrogen.

In an embodiment, in Formula 1, a3 may not be 0, and a group representedby *-(L₃)_(b3)-(R₃)_(c3) in a number of a3 may satisfy Condition A andCondition B(1):

-   -   Condition A    -   L₃ is a single bond.    -   Condition B(1)    -   R₃ is    -   a C₄-C₂₀ alkyl group unsubstituted or substituted with        deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano        group, a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexyl        group, a cycloheptyl group, a cyclooctyl group, an adamantyl        group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof; or    -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclooctyl group, an adamantyl group, a norbornenyl group, a        cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl        group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl        group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl        group, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl        group, or a terphenyl group, each unsubstituted or substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀        alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.

In an embodiment, in Formula 1, a4 may not be 0, and a group representedby *-(L₄)_(b4)-(R₄)_(c4) in a number of a4 may satisfy Condition 1,Condition 2, or combination thereof:

-   -   Condition 1    -   R₄ in a number of c4 is a substituted or unsubstituted C₆-C₆₀        aryl group, a substituted or unsubstituted C₁-C₆₀ heteroaryl        group, a substituted or unsubstituted monovalent non-aromatic        condensed polycyclic group, or a substituted or unsubstituted        monovalent non-aromatic condensed heteropolycyclic group.    -   Condition 2    -   L₄ is not a single bond.

In an embodiment, in Formula 1, a4 may not be 0, and a group representedby *-(L₄)_(b4)-(R₄)_(c4) in a number of a4 may satisfy Condition 1(1),Condition 2(1), or combination thereof:

-   -   Condition 1(1)    -   R₄ in a number of c4 is a cyclopentyl group, a cyclohexyl group,        a cycloheptyl group, a cyclooctyl group, an adamantyl group, a        norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,        a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a        bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, a        bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, or a terphenyl group, each        unsubstituted or substituted with deuterium, —F, —CD₃, —CD₂H,        —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, a C₁-C₂₀ alkyl group,        a deuterium-containing C₂-C₂₀ alkyl group, a C₁-C₂₀ alkoxy        group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl        group, a cyclooctyl group, an adamantyl group, a norbornenyl        group, a cyclopentenyl group, a cyclohexenyl group, a        cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a        bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, a        bicyclo[2.2.2]octyl group, a (C₁-C₂₀ alkyl)cyclopentyl group, a        (C₁-C₂₀ alkyl)cyclohexyl group, a (C₁-C₂₀ alkyl)cycloheptyl        group, a (C₁-C₂₀ alkyl)cyclooctyl group, a (C₁-C₂₀        alkyl)adamantyl group, a (C₁-C₂₀ alkyl)norbornenyl group, a        (C₁-C₂₀ alkyl)cyclopentenyl group, a (C₁-C₂₀ alkyl)cyclohexenyl        group, a (C₁-C₂₀ alkyl)cycloheptenyl group, a (C₁-C₂₀        alkyl)bicyclo[1.1.1]pentyl group, a (C₁-C₂₀        alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.    -   Condition 2(1)    -   L₄ is a benzene group unsubstituted or substituted with        deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano        group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀ alkyl        group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl        group, a cycloheptyl group, a cyclooctyl group, an adamantyl        group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.

In an embodiment, in Formula 1, a4 may not be 0, and a group representedby *-(L₄)_(b4)-(R₄)_(c4) in a number of a4 may satisfy Condition 3,Condition 4, Condition 5, or combination thereof:

-   -   Condition 3    -   R₄ in a number of c4 is a substituted C₆-C₆₀ aryl group.    -   Condition 4    -   L₄ is a C₅-C₃₀ carbocyclic group substituted with an R_(10a)        group,    -   Condition 5    -   L₄ is a C₅-C₃₀ carbocyclic group that is unsubstituted or        substituted with an R_(10a) group and R₄ is not hydrogen.

In an embodiment, in Formula 1, a4 may not be 0, and a group representedby *-(L₄)_(b4)-(R₄)_(c4) in a number of a4 may satisfy Condition 3(1),Condition 4(1), Condition 5(1), or combination thereof:

-   -   Condition 3(1)    -   R₄ in a number of c4 is a phenyl group, a (C₁-C₂₀ alkyl)phenyl        group, a biphenyl group, or a terphenyl group, each substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀        alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.    -   Condition 4(1)    -   L₄ is a benzene group substituted with deuterium, —F, —CD₃,        —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, a C₁-C₂₀ alkyl        group, a deuterium-containing C₂-C₂₀ alkyl group, a C₁-C₂₀        alkoxy group, a cyclopentyl group, a cyclohexyl group, a        cycloheptyl group, a cyclooctyl group, an adamantyl group, a        norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,        a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a        bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, a        bicyclo[2.2.2]octyl group, a (C₁-C₂₀ alkyl)cyclopentyl group, a        (C₁-C₂₀ alkyl)cyclohexyl group, a (C₁-C₂₀ alkyl)cycloheptyl        group, a (C₁-C₂₀ alkyl)cyclooctyl group, a (C₁-C₂₀        alkyl)adamantyl group, a (C₁-C₂₀ alkyl)norbornenyl group, a        (C₁-C₂₀ alkyl)cyclopentenyl group, a (C₁-C₂₀ alkyl)cyclohexenyl        group, a (C₁-C₂₀ alkyl)cycloheptenyl group, a (C₁-C₂₀        alkyl)bicyclo[1.1.1]pentyl group, a (C₁-C₂₀        alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.    -   Condition 5(1)    -   L₄ is a benzene group unsubstituted or substituted with        deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano        group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀ alkyl        group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl        group, a cycloheptyl group, a cyclooctyl group, an adamantyl        group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof, and    -   R₄ is    -   deuterium, —F, a cyano group, C₁-C₂₀ alkyl group, or a C₁-C₂₀        alkoxy group;    -   a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, each substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₁₀ alkyl group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof; or    -   a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a        cyclooctyl group, an adamantyl group, a norbornenyl group, a        cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl        group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl        group, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl        group, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl        group, or a terphenyl group, each unsubstituted or substituted        with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a        cyano group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀        alkyl group, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a        cyclohexyl group, a cycloheptyl group, a cyclooctyl group, an        adamantyl group, a norbornenyl group, a cyclopentenyl group, a        cyclohexenyl group, a cycloheptenyl group, a        bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a        bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a        (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl        group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀        alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a        (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl        group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀        alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl        group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀        alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀        alkyl)phenyl group, a biphenyl group, a terphenyl group, or any        combination thereof.

In an embodiment, in Formula 1, a51 and a52 may each independently be 0,1 or 2, the sum of a51 and a52 may be 1 or 2, and a53 may be 1 or 2.

* and *′ each indicate a binding site to a neighboring atom.

For example, a group represented by

in Formula 1 may be a group represented by one of Formulae A1(1) toA1(30):

In Formulae A1(1) to A1(30),

-   -   Y₁, L₁, b1, R₁, and c1 may each independently be the same as        described herein,    -   X₁₁ may be O, S, N(R₁₁), C(R₁₁)(R₁₂), or Si(R₁₁)(R₁₂),    -   R₁₁ to R₁₈ may each independently be the same as described in        connection with R₁,    -   a12 may be an integer from 0 to 2,    -   a13 may be an integer from 0 to 3,    -   a14 may be an integer from 0 to 4,    -   a15 may be an integer from 0 to 5,    -   a16 may be an integer from 0 to 6,    -   *′ indicates a binding site to X₁ in Formula 1, and    -   indicates a binding site to Y₃ in Formula 1.

The group represented by

in Formula 1 may include deuterium, a deuterium-containing C₁-C₆₀ alkylgroup unsubstituted or substituted with a C₃-C₁₀ cycloalkyl group, orany combination thereof. The number of deuterium atoms in the grouprepresented by

in Formula 1 may be from 1 to 20, for example, from 1 to 15, from 1 to10, or from 1 to 5.

In an embodiment, a group represented by

in Formula 1 may be a group represented by one of Formulae A2(1) toA2(4):

In Formulae A2(1) to A2(4),

-   -   X₂, L₂, b2, R₂, and c2 may each independently be the same as        described herein,    -   a22 may be an integer from 0 to 2,    -   a23 may be an integer from 0 to 3,    -   indicates a binding site to L₅₁ in Formula 1,    -   *″ indicates a binding site to ring CY₃ in Formula 1,    -   *′ indicates a binding site to M in Formula 1, and    -   * indicates a binding site to ring CY₁ in Formula 1.

The group represented by

in Formula 1 may include deuterium, a deuterium-containing C₁-C₆₀ alkylgroup unsubstituted or substituted with a C₃-C₁₀ cycloalkyl group, orany combination thereof. The number of deuterium atoms in the grouprepresented by

in Formula 1 may be from 1 to 20, for example, from 1 to 15, from 1 to10, or from 1 to 5.

In an embodiment, a group represented by

in Formula 1 may be a group represented by one of Formulae A3(1) toA3(17):

In Formulae A3(1) to A3(17),

-   -   X₃, L₃, b3, R₃, and c3 may each independently be the same as        described herein,    -   X₃₁ may be O, S, N(R₃₁), C(R₃₁)(R₃₂), or Si(R₃₁)(R₃₂),    -   R₃₁ to R₃₈ may each independently be the same as described in        connection with    -   a32 may be an integer from 0 to 2,    -   a33 may be an integer from 0 to 3,    -   a34 may be an integer from 0 to 4,    -   a35 may be an integer from 0 to 5,    -   *″ indicates a binding site to ring CY₂ in Formula 1,    -   *′ indicates a binding site to M in Formula 1, and    -   indicates a binding site to T₁ in Formula 1.

The group represented by

in Formula 1 may include deuterium, a deuterium-containing C₁-C₆₀ alkylgroup unsubstituted or substituted with a C₃-C₁₀ cycloalkyl group, orany combination thereof. The number of deuterium atoms in the grouprepresented by

in Formula 1 may be from 1 to 20, for example, from 1 to 15, from 1 to10, or from 1 to 5.

In an embodiment, a group represented by

in Formula 1 may be a group represented by one of Formulae A4(1) toA4(45):

In Formulae A4(1) to A4(45),

-   -   X₄, L₄, b4, R₄, and c4 may each independently be the same as        described herein,    -   X₄₁ may be O, S, N(R₄₁), C(R₄₁)(R₄₂), or Si(R₄₁)(R₄₂),    -   R₄₁ to R₄₈ may each independently be the same as described in        connection with R₄,    -   a42 may be an integer from 0 to 2,    -   a43 may be an integer from 0 to 3,    -   a44 may be an integer from 0 to 4,    -   a45 may be an integer from 0 to 5,    -   a46 may be an integer from 0 to 6,    -   *′ indicates a binding site to M in Formula 1, and    -   indicates a binding site to T₁ in Formula 1.

The group represented by

in Formula 1 may include deuterium, a deuterium-containing C₁-C₆₀ alkylgroup unsubstituted or substituted with a C₃-C₁₀ cycloalkyl group, orany combination thereof. The number of deuterium atoms in the grouprepresented by

in Formula 1 may be from 1 to 20, for example, from 1 to 15, from 1 to10, or from 1 to 5.

In an embodiment, in Formula 1, a group represented by

may be a group represented by one of Formulae CY1(1) to CY1(8), and/or

-   -   a group represented by

may be a group represented by one of Formulae CY2(1) to CY2(4), and/or

-   -   a group represented by

may be a group represented by one of Formulae CY3(1) to CY3(24), and/or

-   -   a group represented by

may be a group represented by one of Formulae CY4(1) to CY4(74), butembodiments of the present disclosure are not limited thereto:

In Formulae CY1(1) to CY1(8), CY2(1) to CY2(4), CY3(1) to CY3(24), andCY4(1) to CY4(74),

-   -   X₂ to X₄, Y₁, L₁ to L₄, b1 to b4, R₁ to R₄, and c1 to c4 may        each independently be the same as described herein,    -   X₃₁ may be O, S, N(R₃₁), C(R₃₁)(R₃₂), or Si(R₃₁)(R₃₂),    -   X₄₁ may be O, S, N(R₄₁), C(R₄₁)(R₄₂), or Si(R₄₁)(R₄₂),    -   L_(1a) and L_(1b) may each independently be the same as        described in connection with L₁,    -   R_(1a) and R_(1b) may each independently be the same as        described in connection with R₁,    -   L_(3a) and L_(3b) may each independently be the same as        described in connection with L₃,    -   R_(3a), R_(3b), R₃₁, and R₃₂ may each independently be the same        as described in connection with R₃,    -   L_(4a) to L_(4d) may each independently be the same as described        in connection with L₄,    -   R_(4a) to R_(4d), R₄₁, and R₄₂ may each independently be the        same as described in connection with R₄,    -   *-(L₁)_(b1)-(R₁)_(c1), *-(L_(1a))_(b1)-(R_(1a))_(c1),        *-(L_(1b))_(b1)-(R_(1a))_(c1), *-(L₂)_(b2)-(R₂)_(c2),        *-(L₃)_(b3)-(R₃)_(c3), * (L_(3a))_(b3)-(R_(3a))_(c3),        *-(L_(3b))_(b3)-(R_(3a))_(c3), *-(L₄)_(b4)-(R₄)_(c4),        *-(L_(4a))_(b4)-(R_(4a))_(c4), *-(L_(4b))_(b4)-(R_(4a))_(c4),        *-(L_(4c))_(b4)-(R_(4c))_(c4), and *-(L_(4d))_(b4)-(R_(4d))_(c4)        may not be hydrogen, and * indicates a binding site to a        neighboring atom,    -   in Formulae CY1(1) to CY1(8), *′ indicates a binding site to X₁        in Formula 1,    -   in Formulae CY2(1) to CY2(4), CY3(1) to CY3(24), and CY4(1) to        CY4(74), *′ indicates a binding site to M in Formula 1,    -   in Formulae CY1(1) to CY1(8), * indicates a binding site to Y₃        in Formula 1,    -   in Formulae CY2(1) to CY2(4), * indicates a binding site to ring        CY₁ in Formula 1, and *″ indicates a binding site to ring CY₃ in        Formula 1,    -   in Formulae CY3(1) to CY3(24), *″ indicates a binding site to        ring CY₂ in Formula 1, and * indicates a binding site to T₁ in        Formula 1, and    -   in Formulae CY4(1) to CY4(74), * indicates a binding site to T₁        in Formula 1.

In an embodiment, a group represented by

may be a group represented by Formula CY4-1 or CY4-2:

-   -   in Formulae CY4-1 and CY4-2,    -   X₄, L₄, b4, R₄, and c4 may each independently be the same as        described herein,    -   Z₄₁ to Z₄₄ may each independently be the same as described in        connection with R₄ herein,    -   *′ indicates a binding site to M in Formula 1, and    -   indicates a binding site to T₁ in Formula 1.

For example, Formulae CY4-1 and CY4-2 may satisfy:

1) Condition 1, Condition 2, or any combination thereof (or, Condition1(1), Condition 2(1), or any combination thereof), and/or

2) Condition 3, Condition 4, Condition 5, or any combination thereof(or, Condition 3(1), Condition 4(1), Condition 5(1), or any combinationthereof).

In an embodiment, in Formula 1, a group represented by

may be a group represented by Formula CY1(1) or CY1(6), and/or

a group represented by

may be a group represented by Formula CY2(1), and/or

a group represented by

may be a group represented by Formula CY3(3), and/ora group represented by

may be a group represented by Formula CY4(3), CY4(4) or CY4(16).

In an embodiment, a group represented by

in Formula 1 may be a group represented by one of Formulae 51-1 to51-32:

In Formulae 51-1 to 51-32, R₅₁, R₅₂, c52, A₅₁, and A₅₂ may eachindependently be the same as described herein, R₅₃ and c53 may eachindependently be the same as described in connection with R₅₂ and c52,c512 is an integer of 0 to 2, c513 is an integer of 0 to 3, and *indicates a binding site to L₅₁.

In an embodiment, the organometallic compound may be represented byFormula 1-1 or 1-2:

in Formulae 1-1 and 1-2,

M, X₁ to X₄, Y₁, Y₃ to Y₅, L₄, L₅₁, b4, b51, R₅₁, R₅₂, c51, c52, A₅₁,A₅₂, a51, a52 and a53 may each independently be the same as describedherein,

Z₁₁ to Z₁₄ may each independently be the same as described in connectionwith R₁,

Z₂₁ to Z₂₃ may each independently be the same as described in connectionwith R₂,

Z₃₁ to Z₃₃ may each independently be the same as described in connectionwith R₃,

Z₄₁ to Z₄₄ may each independently be the same as described in connectionwith R₄,

two or more groups of Z₁₁ to Z₁₄ may be optionally linked to form aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group,

two or more groups of Z₂₁ to Z₂₃ may be optionally linked to form aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group,

two or more groups of Z₃₁ to Z₃₃ may be optionally linked to form aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group,

two or more groups of Z₄₁ to Z₄₄ may be optionally linked to form aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group, and

R_(10a) is the same as described in connection with R₁.

Descriptions for Formula 1 described herein can be applied for Formulae1-1 and 1-2.

For example,

1) Formulae 1-1 and 1-2 may satisfy Condition A, Condition B, or anycombination thereof (or, Condition A, Condition B(1), or any combinationthereof), and/or

2) Formulae 1-1 and 1-2 may satisfy Condition 1, Condition 2, or anycombination thereof (or, Condition 1(1), Condition 2(1), or anycombination thereof), and/or

3) Formulae 1-1 and 1-2 may satisfy Condition 3, Condition 4, Condition5, or any combination thereof (or, Condition 3(1), Condition 4(1),Condition 5(1), or any combination thereof), and/or

4) a group represented by

in Formulae 1-1 and 1-2 may be a group represented by one of Formulae51-1 to 51-32.

In an embodiment, Z₁₂, Z₁₄, Z₂₁ to Z₂₃, Z₃₁, Z₃₃ and Z₄₁ to Z₄₄ inFormulae 1-1 and 1-2 may each independently be hydrogen, deuterium,—CH₃, or —CD₃.

In an embodiment, Z₁₂, Z₁₄, Z₂₁ to Z₂₃, Z₃₁, Z₃₃ and Z₄₁ to Z₄₄ inFormulae 1-1 and 1-2 may each independently be hydrogen, or deuterium.

In an embodiment, Z₁₁ and Z₁₃ in Formulae 1-1 and 1-2 may not behydrogen and Z₁₁ and Z₁₃ may include a deuterium.

In an embodiment, Z₁₁ and Z₁₃ in Formulae 1-1 and 1-2 may not behydrogen and Z₁₁ and Z₁₃ may be identical to each other.

In an embodiment, Z₁₁ and Z₁₃ in Formulae 1-1 and 1-2 may not behydrogen and Z₁₁ and Z₁₃ may be different from each other.

In Formula 1, i) two or more groups of a plurality of R₁ groups mayoptionally be linked to form a C₅-C₃₀ carbocyclic group that isunsubstituted or substituted with an R_(10a) group or a C₂-C₃₀heterocyclic group that is unsubstituted or substituted with an R_(10a)group, ii) two or more groups of a plurality of R₂ groups may optionallybe linked to form a C₅-C₃₀ carbocyclic group that is unsubstituted orsubstituted with an R_(10a) group or a C₂-C₃₀ heterocyclic group that isunsubstituted or substituted with an R_(10a) group, iii) two or moregroups of a plurality of R₃ groups may optionally be linked to form aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group, iv) two or more groups of a pluralityof R₄ groups may optionally be linked to form a C₅-C₃₀ carbocyclic groupthat is unsubstituted or substituted with an R_(10a) group or a C₂-C₃₀heterocyclic group that is unsubstituted or substituted with an R_(10a)group, and v) two or more groups of R₁ to R₆ may optionally be linked toform a C₅-C₃₀ carbocyclic group that is unsubstituted or substitutedwith an R_(10a) group or a C₂-C₃₀ heterocyclic group that isunsubstituted or substituted with an R_(10a) group. An R_(10a) group maybe the same as described in connection with R₁.

For example, a C₅-C₃₀ carbocyclic group (that is unsubstituted orsubstituted with an R_(10a) group) and a C₂-C₃₀ heterocyclic group (thatis unsubstituted or substituted with an R_(10a) group) may eachindependently be a cyclopentane group, a silole group, an azasilolegroup, a diazasilole group, a triazasilole group, an adamantane group, anorbornene group, a bicyclo[1.1.1]pentane group, a bicyclo[2.1.1]hexanegroup, a bicyclo[2.2.1]heptane group, a bicyclo[2.2.2]octane group, acyclohexane group, a cyclohexene group, a benzene group, a naphthalenegroup, an anthracene group, a phenanthrene group, a triphenylene group,a pyrene group, a chrysene group, a cyclopentadiene group, a1,2,3,4-tetrahydronaphthalene group, a thiophene group, a furan group, abenzoborole group, a benzophosphole group, an indene group, abenzosilole group, a benzogermole group, a benzothiophene group, abenzoselenophene group, a benzofuran group, a carbazole group, adibenzoborole group, a dibenzophosphole group, a fluorene group, adibenzosilole group, a dibenzogermole group, a dibenzothiophene group, adibenzoselenophene group, a dibenzofuran group, adibenzothiophene-5-oxide group, a 9H-fluorene-9-one group, adibenzothiophene 5,5-dioxide group, an azaindole group, anazabenzoborole group, an azabenzophosphole group, an azaindene group, anazabenzosilole group, an azabenzogermole group, an azabenzothiophenegroup, an azabenzoselenophene group, an azabenzofuran group, anazacarbazole group, an azadibenzoborole group, an azadibenzophospholegroup, an azafluorene group, an azadibenzosilole group, anazadibenzogermole group, an azadibenzothiophene group, anazadibenzoselenophene group, an azadibenzofuran group, anazadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, anazadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidinegroup, a pyrazine group, a pyridazine group, a triazine group, aquinoline group, an isoquinoline group, a quinoxaline group, aquinazoline group, a phenanthroline group, a pyrrole group, a pyrazolegroup, an imidazole group, a triazole group, an oxazole group, anisoxazole group, a thiazole group, an isothiazole group, an oxadiazolegroup, a thiadiazole group, a benzopyrazole group, a benzimidazolegroup, a benzoxazole group, a benzothiazole group, a benzoxadiazolegroup, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group,or a 5,6,7,8-tetrahydroquinoline group, each unsubstituted orsubstituted with an R_(1a) group, but embodiments of the presentdisclosure are not limited thereto.

Non-limiting examples of the C₁-C₆₀ alkyl group, C₁-C₂₀ alkyl groupand/or C₁-C₁₀ alkyl group include a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group,an isobutyl group, a tert-butyl group, an n-pentyl group, a tert-pentylgroup, a neopentyl group, an isopentyl group, a sec-pentyl group, a3-pentyl group, a sec-isopentyl group, an n-hexyl group, an isohexylgroup, a sec-hexyl group, a tert-hexyl group, an n-heptyl group, anisoheptyl group, a sec-heptyl group, a tert-heptyl group, an n-octylgroup, an isooctyl group, a sec-octyl group, a tert-octyl group, ann-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group,an n-decyl group, an isodecyl group, a sec-decyl group, or a tert-decylgroup, each unsubstituted or substituted with a methyl group, an ethylgroup, an n-propyl group, an isopropyl group, an n-butyl group, asec-butyl group, an isobutyl group, a tert-butyl group, an n-pentylgroup, a tert-pentyl group, a neopentyl group, an isopentyl group, asec-pentyl group, a 3-pentyl group, a sec-isopentyl group, an n-hexylgroup, an isohexyl group, a sec-hexyl group, a tert-hexyl group, ann-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptylgroup, an n-octyl group, an isooctyl group, a sec-octyl group, atert-octyl group, an n-nonyl group, an isononyl group, a sec-nonylgroup, a tert-nonyl group, an n-decyl group, an isodecyl group, asec-decyl group, a tert-decyl group, or any combination thereof, and thelike, but embodiments of the present disclosure are not limited thereto.

Non-limiting examples of the C₁-C₆₀ alkoxy group, C₁-C₂₀ alkoxy groupand/or C₁-C₁₀ alkoxy group include a methoxy group, an ethoxy group, apropoxy group or a butoxy group, and the like, but embodiments of thepresent disclosure are not limited thereto.

Non-limiting examples of the C₃-C₁₀ cycloalkyl group include acyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexylgroup, a cycloheptyl group, a cyclooctyl group, an adamantyl group, abicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, abicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, and the like,but embodiments of the present disclosure are not limited thereto.

An angle formed by a plane including the transition dipole moment of theorganometallic compound represented by Formula 1 and a plane includingfour atoms of a tetradentate ligand linked to a metal M of Formula 1 maybe about 10° or less. In addition, a horizontal orientation ratio of thetransition dipole moment of the organometallic compound represented byFormula 1 may be in a range of about 80% to about 100%.

For example, the angle formed by the plane including the transitiondipole moment of the organometallic compound and the plane including thefour atoms of the tetradentate ligand linked to the metal (or platinum)of Formula 1 may be 0° to 10°, 0° to 9°, 0° to 8°, 0° to 7°, 0° to 6°,0° to 5°, 0° to 4°, 0° to 3°, 0° to 2°, or 0° to 1°, but embodiments ofthe present disclosure are not limited thereto. When the angle formed bythe plane including the transition dipole moment of the organometalliccompound represented by the Formula 1 and the plane including the fouratoms of the tetradentate ligand linked to the metal of Formula 1 iswithin these ranges, the organometallic compound may have excellentplanarity, and a thin film formed by using the organometallic compoundmay have excellent electric characteristics.

In an embodiment, the horizontal orientation ratio of the transitiondipole moment of the organometallic compound may be in a range of, forexample, 80% to 100%, 81% to 100%, 82% to 100%, 83% to 100%, 84% to100%, 85% to 100%, 86% to 100%, 87% to 100%, 88% to 100%, 89% to 100%,90% to 100%, 91% to 100%, 92% to 100%, 93% to 100%, 94% to 100%, 95% to100%, 96% to 100%, 97% to 100%, 98% to 100%, 99% to 100%, or 100%, butembodiments of the present disclosure are not limited thereto.

The horizontal orientation ratio of the transition dipole moment means aratio of the organometallic compound having a transition dipole momenthorizontal to the film including the organometallic compound to thetotal organometallic compound in the film including the organometalliccompound.

The horizontal orientation ratio of the transition dipole moment may beevaluated by using an angle-dependent PL measurement apparatus. Theangle-dependent PL measurement apparatus may be understood by referringto Korean Patent Application No. 10-2013-0150834, the content of whichis incorporated herein in its entirety by reference.

Since the organometallic compound has a high horizontal orientationratio of a transition dipole moment, the organometallic compound has alarge horizontal orientation transition dipole moment (that is, a largehorizontal optical orientation). Therefore, a large amount of electricfield traveling in a direction perpendicular to the film including theorganometallic compound may be emitted. Light emitted due to such amechanism may have high external extraction efficiency (that is,efficiency of extracting light emitted in the organometallic compoundfrom a device (for example, an organic light-emitting device) includinga film (for example, an emission layer described below) including theorganometallic compound) to the outside, and thus, an electronic device,for example, an organic light-emitting device, which includes theorganometallic compound, may have high luminescent efficiency.

The terms “an azaindole group, an azabenzoborole group, anazabenzophosphole group, an azaindene group, an azabenzosilole group, anazabenzogermole group, an azabenzothiophene group, anazabenzoselenophene group, an azabenzofuran group, an azacarbazolegroup, an azadibenzoborole group, an azadibenzophosphole group, anazafluorene group, an azadibenzosilole group, an azadibenzogermolegroup, an azadibenzothiophene group, an azadibenzoselenophene group, anazadibenzofuran group, an azadibenzothiophene 5-oxide group, anaza-9H-fluorene-9-one group, and an azadibenzothiophene 5,5-dioxidegroup” as used herein each refer to a heterocyclic group having the samebackbone as that of each of “an indole group, a benzoborole group, abenzophosphole group, an indene group, a benzosilole group, abenzogermole group, a benzothiophene group, a benzoselenophene group, abenzofuran group, a carbazole group, a dibenzoborole group, adibenzophosphole group, a fluorene group, a dibenzosilole group, adibenzogermole group, a dibenzothiophene group, a dibenzoselenophenegroup, a dibenzofuran group, a dibenzothiophene 5-oxide group, a9H-fluorene-9-one group, and a dibenzothiophene 5,5-dioxide group”,respectively, wherein an ring-forming carbons of the rings above issubstituted with nitrogen.

In addition, R_(10a) is defined the same as R₁.

For example, the organometallic compound represented by Formula 1 mayinclude a deuterium.

In an embodiment, the organometallic compound may be one of thefollowing Compounds 1 to 3599:

In Formula 1, A₅₁ may be a C₄-C₆₀ alkyl group, A₅₂ may be deuterium or adeuterium-containing C₁-C₆₀ alkyl group unsubstituted or substitutedwith a C₃-C₁₀ cycloalkyl group, a51 (the number of A₅₁) and a52 (thenumber of A₅₂) may each independently be an integer from 0 to 10,provided that the sum of a51 and a52 may be 1 or more. That is, inFormula 1, ring CY₅₁ is substituted with a group represented by A₅₁, agroup represented by A₅₂, or any combination thereof. Since ring CY₅₁ issubstituted with an electron donating group, an electronic device, forexample, an organic light-emitting device, which includes theorganometallic compound represented by Formula 1, may have improvedluminescent efficiency and lifespan.

In an embodiment, A₅₁ in Formula 1 may be a group having the formula—C(R₅₁₁)(R₅₁₂)(R₅₁₃), wherein R₅₁₁, R₅₁₂, and R₅₁₃ are eachindependently a C₁-C₆₀ alkyl group, for example, a C₁-C₅₀ alkyl group, aC₁-C₄₀ alkyl group, a C₁-C₃₀ alkyl group, a C₁-C₂₀ alkyl group, a C₁-C₁₀alkyl group, or a C₁-C₅ alkyl group. While not wishing to be bound bytheory, it is understood that when A₅₁ has the formula—C(R₅₁₁)(R₅₁₂)(R₅₁₃), the organometallic compound represented by Formula1, may have improved luminescent efficiency and lifespan compared to thecompounds in which at least one of R₅₁₁, R₅₁₂, or R₅₁₃ is hydrogen.

In an embodiment, A₅₂ in Formula 1 may be a group having the formula—CD(R₅₂₁)(R₅₂₂), wherein R₅₂₁ and R₅₂₂ are each independently a C₁-C₆₀alkyl group, a C₁-C₆₀ alkyl group substituted with deuterium, a C₃-C₁₀cycloalkyl group, or any combination thereof. In an embodiment, A₅₂ inFormula 1 may be a group having the formula —CD₂(R₅₂₁), wherein R₅₂₁ isthe same as defined above. In still another embodiment, A₅₂ may be afully deuterated group, such as CD₃, C₂D₅, C₃D₇, C₄D₉, but is notlimited thereto. While not wishing to be bound by theory, it isunderstood that when A₅₂ has the formula —CD(R₅₂₁)(R₅₂₂), the formula—CD₂(R₅₂₁), or wherein A₅₂ is a fully deuterated group, theorganometallic compound represented by Formula 1, may have improvedluminescent efficiency and lifespan compared to the compounds in whichat least one of R₅₂₁ or R₅₂₂ is hydrogen.

A₅₂ may be a partially or fully deuterated C₁-C₆₀ alkyl groupunsubstituted or substituted with a C₃-C₁₀ cycloalkyl group. When thedegree of deuteration is 100%, the group A₅₂ is fully deuterated. Whenthe degree of deuteration is lower than 100%, the group A₅₂ is partiallydeuterated. The degree of deuteration of the group A₅₂ may be calculatedby using Equation 10:

degree of deuteration (%)=n _(D2)/(n _(H2) +n _(D2))×100.  Equation 10

In Equation 10, n_(H2) represents the total number of hydrogens includedin the group A₅₂, and

n_(D2) represents the total number of deuterium atoms included in thegroup A₅₂.

In an embodiment, the degree of deuteration of the group A₅₂ may beabout 5% or more, about 10% or more, about 20% or more, about 30% ormore, about 40% or more, about 50% or more, about 60% or more, about 70%or more, about 90% or more, about 95% or more, about 96% or more, about97% or more, about 98% or more, or about 99% or more, but embodiments ofthe present disclosure are not limited thereto.

In addition, a53 that is the number of groups represented by

in Formula 1 may be an integer from 1 to 10. That is, since a53 inFormula 1 is not 0, ring CY₅₁ in Formula 1 is substituted with a grouprepresented by

Therefore, due to the resonance effect caused by the group representedby

an electronic device, for example, an organic light-emitting device,which includes the organometallic compound represented by Formula 1, mayhave improved luminescent efficiency and lifespan. In addition, althoughnot limited by a specific theory, a group represented by

in Formula 1 is protected from electrons, heat, or the like by the grouprepresented by

Therefore, an electronic device, for example, an organic light-emittingdevice, which includes the organometallic compound represented byFormula 1, may have improved luminescent efficiency and lifespan.

In Formula 1, the sum of a51 and a52 may be 1 or more and a53 may be aninteger from 1 to 10. Thus, in an embodiment, the organometalliccompound may simultaneously include

and A₅₁. In another embodiment, the organometallic compound maysimultaneously include

and A₅₂.

For example, highest occupied molecular orbital (HOMO), lowestunoccupied molecular orbital (LUMO), energy band gap, singlet (Si), andtriplet (Ti) energy levels of Compounds 1 to 8 were evaluated by using aDFT method of Gaussian program (structurally optimized at a level ofB3LYP, 6-31G(d,p)). Evaluation results are shown in Table 1 below.

TABLE 1 Energy Compound HOMO LUMO band gap S₁ T₁ No. (eV) (eV) (eV) (eV)(eV) 1 −4.647 −1.681 2.965 2.489 2.333 2 −4.660 −1.694 2.966 2.489 2.3343 −4.584 −1.642 2.942 2.486 2.336 4 −4.584 −1.642 2.942 2.486 2.336 5−4.647 −1.681 2.965 2.489 2.333 6 −4.647 −1.681 2.965 2.489 2.333 7−4.598 −1.624 2.974 2.488 2.344 8 −4.621 −1.695 2.926 2.486 2.311

From Table 1, it is confirmed that the organometallic compoundrepresented by Formula 1 has such electric characteristics that aresuitable for use in an electronic device, for example, for use as adopant for an organic light-emitting device.

Synthesis methods of the organometallic compound represented by Formula1 may be understood by one of ordinary skill in the art by referring toSynthesis Examples provided below.

The organometallic compound represented by Formula 1 is suitable for usein an organic layer of an organic light-emitting device, for example,for use as a dopant in an emission layer of the organic layer. Thus,another aspect provides an organic light-emitting device that includes:a first electrode; a second electrode; and an organic layer that isdisposed between the first electrode and the second electrode, whereinthe organic layer includes an emission layer and an organometalliccompound represented by Formula 1.

The organic light-emitting device may have, due to the inclusion of anorganic layer including the organometallic compound represented byFormula 1, a low driving voltage, high quantum efficiency, a lowroll-off ratio, and a long lifespan.

The organometallic compound of Formula 1 may be used between a pair ofelectrodes of an organic light-emitting device. For example, theorganometallic compound represented by Formula 1 may be included in theemission layer. In this embodiment, the organometallic compound may actas a dopant, and the emission layer may further include a host (that is,an amount of the organometallic compound represented by Formula 1 issmaller than an amount of the host).

In an embodiment, the emission layer may include a host and a dopant,and the dopant may include the organometallic compound represented byFormula 1. The organometallic compound represented by Formula 1 may be ared phosphorescent dopant.

The expression “(an organic layer) includes an organometallic compound”as used herein may include an embodiment in which “(an organic layer)includes identical organometallic compounds represented by Formula 1”and an embodiment in which “(an organic layer) includes two or moredifferent organometallic compounds represented by Formula 1.”

For example, the organic layer may include, as the organometalliccompound, only Compound 1. In this embodiment, Compound 1 may beincluded in an emission layer of the organic light-emitting device. Inan embodiment, the organic layer may include, as the organometalliccompound, Compound 1 and Compound 2. In this embodiment, Compound 1 andCompound 2 may be included in an identical layer (for example, Compound1 and Compound 2 may both be included in an emission layer).

The first electrode may be an anode, which is a hole injectionelectrode, and the second electrode may be a cathode, which is anelectron injection electrode; or the first electrode may be a cathode,which is an electron injection electrode, and the second electrode maybe an anode, which is a hole injection electrode.

In an embodiment, in the organic light-emitting device, the firstelectrode may be an anode, and the second electrode may be a cathode,and the organic layer may further include a hole transport regiondisposed between the first electrode and the emission layer and anelectron transport region disposed between the emission layer and thesecond electrode, wherein the hole transport region may include a holeinjection layer, a hole transport layer, an electron blocking layer, orany combination thereof, and the electron transport region may include ahole blocking layer, an electron transport layer, an electron injectionlayer, or any combination thereof.

The term “organic layer” as used herein refers to a single layer and/ora plurality of layers disposed between the first electrode and thesecond electrode of the organic light-emitting device. The “organiclayer” may include, in addition to an organic compound, anorganometallic complex including metal.

The FIGURE is a schematic view of an organic light-emitting device 10according to an embodiment. Hereinafter, the structure of an organiclight-emitting device according to an embodiment and a method ofmanufacturing an organic light-emitting device according to anembodiment will be described in connection with the FIGURE. The organiclight-emitting device 10 includes a first electrode 11, an organic layer15, and a second electrode 19, which are sequentially stacked.

A substrate may be additionally disposed under the first electrode 11 orabove the second electrode 19. For use as the substrate, any substratethat is used in general organic light-emitting devices may be used, andthe substrate may be a glass substrate or a transparent plasticsubstrate, each having excellent mechanical strength, thermal stability,transparency, surface smoothness, ease of handling, and waterresistance.

The first electrode 11 may be formed by depositing or sputtering amaterial for forming the first electrode 11 on the substrate. The firstelectrode 11 may be an anode. The material for forming the firstelectrode 11 may be a material(s) with a high work function tofacilitate hole injection. The first electrode 11 may be a reflectiveelectrode, a semi-transmissive electrode, or a transmissive electrode.The material for forming the first electrode may be, for example, indiumtin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO₂), and zincoxide (ZnO). In an embodiment, magnesium (Mg), aluminum (Al),aluminum-lithium (Al-L₁), calcium (Ca), magnesium-indium (Mg—In), ormagnesium-silver (Mg—Ag) may be used as the material for forming thefirst electrode.

The first electrode 11 may have a single-layered structure or amulti-layered structure including two or more layers. For example, thefirst electrode 11 may have a three-layered structure of ITO/Ag/ITO, butthe structure of the first electrode 110 is not limited thereto.

The organic layer 15 is disposed on the first electrode 11.

The organic layer 15 may include a hole transport region, an emissionlayer, and an electron transport region.

The hole transport region may be disposed between the first electrode 11and the emission layer.

The hole transport region may include a hole injection layer, a holetransport layer, an electron blocking layer, a buffer layer, or anycombination thereof.

The hole transport region may include only either a hole injection layeror a hole transport layer. In an embodiment, the hole transport regionmay have a hole injection layer/hole transport layer structure or a holeinjection layer/hole transport layer/electron blocking layer structure,which are sequentially stacked in this stated order from the firstelectrode 11.

A hole injection layer may be formed on the first electrode 11 by usinga suitable method for example, vacuum deposition, spin coating, casting,Langmuir-Blodgett (LB) deposition, or any combination thereof.

When a hole injection layer is formed by vacuum deposition, thedeposition conditions may vary according to a compound that is used toform the hole injection layer, and the structure and thermalcharacteristics of the hole injection layer. For example, the depositionconditions may include a deposition temperature of about 100° C. toabout 500° C., a vacuum pressure of about 10⁻⁸ torr to about 10⁻³ torr,and a deposition rate of about 0.01 Angstroms per second (Å/sec) toabout 100 Å/sec. However, the deposition conditions are not limitedthereto.

When the hole injection layer is formed using spin coating, coatingconditions may vary according to the material used to form the holeinjection layer, and the structure and thermal properties of the holeinjection layer. For example, a coating speed may be from about 2,000revolutions per minute (rpm) to about 5,000 rpm, and a temperature atwhich a heat treatment is performed to remove a solvent after coatingmay be from about 80° C. to about 200° C. However, the coatingconditions are not limited thereto.

Conditions for forming a hole transport layer and an electron blockinglayer may be understood by referring to conditions for forming the holeinjection layer.

The hole transport region may include m-MTDATA, TDATA, 2-TNATA, NPB,β-NPB, TPD, Spiro-TPD, Spiro-NPB, methylated-NPB, TAPC, HMTPD,4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA),polyaniline/dodecylbenzene sulfonic acid (PANI/DBSA),poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDOT/PSS),polyaniline/camphor sulfonic acid (PANI/CSA), polyaniline/poly(4-styrenesulfonate) (PANI/PSS), a compound represented by Formula 201, a compoundrepresented by Formula 202, or any combination thereof:

In Formula 201, Ar₁₀₁ and Ar₁₀₂ may each independently be a phenylenegroup, a pentalenylene group, an indenylene group, a naphthylene group,an azulenylene group, a heptalenylene group, an acenaphthylene group, afluorenylene group, a phenalenylene group, a phenanthrenylene group, ananthracenylene group, a fluoranthenylene group, a triphenylenylenegroup, a pyrenylene group, a chrysenylene group, a naphthacenylenegroup, a picenylene group, a perylenylene group, or a pentacenylenegroup, each unsubstituted or substituted with deuterium, —F, —Cl, —Br,—I, a hydroxyl group, a cyano group, a nitro group, an amino group, anamidino group, a hydrazine group, a hydrazone group, a carboxylic acidgroup or a salt thereof, a sulfonic acid group or a salt thereof, aphosphoric acid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀alkenyl group, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkylgroup, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, aC₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, or any combination thereof.

In Formula 201, xa and xb may each independently be an integer from 0 to5, or may be 0, 1, or 2. For example, xa is 1 and xb is 0, but xa and xbare not limited thereto.

In Formulae 201 and 202, R₁₀₁ to R₁₀₈, R₁₁₁ to R₁₁₉, and R₁₂₁ to R₁₂₄may each independently be:

a hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₁₀ alkyl group (for example, a methyl group, an ethylgroup, a propyl group, a butyl group, a pentyl group, a hexyl group, andso on), or a C₁-C₁₀ alkoxy group (for example, a methoxy group, anethoxy group, a propoxy group, a butoxy group, a pentoxy group, and soon);

a C₁-C₁₀ alkyl group or a C₁-C₁₀ alkoxy group, each substituted withdeuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, or anycombination thereof; or

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenylgroup, or a pyrenyl group, each unsubstituted or substituted withdeuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitrogroup, an amino group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₁-C₁₀alkyl group, a C₁-C₁₀ alkoxy group or any combination thereof,

but embodiments of the present disclosure are not limited thereto.

In Formula 201, R₁₀₉ may be a phenyl group, a naphthyl group, ananthracenyl group, or a pyridinyl group, each unsubstituted orsubstituted with deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyanogroup, a nitro group, an amino group, an amidino group, a hydrazinegroup, a hydrazone group, a carboxylic acid group or a salt thereof, asulfonic acid group or a salt thereof, a phosphoric acid group or a saltthereof, a C₁-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, a phenyl group, anaphthyl group, an anthracenyl group, a pyridinyl group, or anycombination thereof.

In an embodiment, the compound represented by Formula 201 may berepresented by Formula 201A, but embodiments of the present disclosureare not limited thereto:

In Formula 201A, R₁₀₁, R₁₁₁, R₁₁₂, and R₁₀₉ are each independently thesame as described above.

For example, the compound represented by Formula 201 and the compoundrepresented by Formula 202 may each independently include Compounds HT1to HT20, but are not limited thereto:

A thickness of the hole transport region may be in a range of about 100Angstroms (Å) to about 10,000 Å, for example, about 100 Å to about 1,000Å. When the hole transport region includes a hole injection layer, ahole transport layer, or any combination thereof, the thickness of thehole injection layer may be in a range of about 100 Å to about 10,000 Å,and for example, about 100 Å to about 1,000 Å, and the thickness of thehole transport layer may be in a range of about 50 Å to about 2,000 Å,and for example, about 100 Å to about 1,500 Å. While not wishing to bebound by theory, it is understood that when the thicknesses of the holetransport region, the hole injection layer, and the hole transport layerare within these ranges, satisfactory hole transporting characteristicsmay be obtained without a substantial increase in driving voltage.

The hole transport region may further include, in addition to thesematerials, a charge-generation material for the improvement ofconductive properties. The charge-generation material may behomogeneously or non-homogeneously dispersed in the hole transportregion.

The charge-generation material may be, for example, a p-dopant. Thep-dopant may be a quinone derivative, a metal oxide, a cyanogroup-containing compound, or any combination thereof, but embodimentsof the present disclosure are not limited thereto. Non-limiting examplesof the p-dopant are a quinone derivative, such astetracyanoquinodimethane (TCNQ) or2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinodimethane (F4-TCNQ); ametal oxide, such as a tungsten oxide or a molybdenum oxide; and a cyanogroup-containing compound, such as Compound HT-D₁, but are not limitedthereto.

The hole transport region may include a buffer layer.

Also, the buffer layer may compensate for an optical resonance distanceaccording to a wavelength of light emitted from the emission layer, andthus, efficiency of a formed organic light-emitting device may beimproved.

Meanwhile, when the hole transport region includes an electron blockinglayer, a material for the electron blocking layer may be a material(s)for the hole transport region described above and materials for a hostto be explained later. However, the material for the electron blockinglayer is not limited thereto. For example, when the hole transportregion includes an electron blocking layer, a material for the electronblocking layer may be mCP, which will be explained later.

Then, an emission layer may be formed on the hole transport region byvacuum deposition, spin coating, casting, LB deposition, or the like.When the emission layer is formed by vacuum deposition or spin coating,the deposition or coating conditions may be similar to those applied informing the hole injection layer although the deposition or coatingconditions may vary according to a compound that is used to form theemission layer.

The emission layer may include a host and a dopant, and the dopant mayinclude the organometallic compound represented by Formula 1.

The host may include TPBi, TBADN, ADN (also referred to as “DNA”), CBP,CDBP, TCP, mCP, Compound H50, Compound H51, or any combination thereof:

When the organic light-emitting device is a full-color organiclight-emitting device, the emission layer may be patterned into a redemission layer, a green emission layer, and/or a blue emission layer. Inan embodiment, due to a stacked structure including a red emissionlayer, a green emission layer, and/or a blue emission layer, theemission layer may emit white light.

When the emission layer includes a host and a dopant, an amount of thedopant may be in a range of about 0.01 parts by weight to about 15 partsby weight based on 100 parts by weight of the host, but embodiments ofthe present disclosure are not limited thereto.

The dopant may include the organometallic compound represented byFormula 1. For example, the dopant may be a red phosphorescent dopant.

A thickness of the emission layer may be in a range of about 100 Å toabout 1,000 Å, for example, about 200 Å to about 600 Å. While notwishing to be bound by theory, it is understood that when the thicknessof the emission layer is within this range, excellent light-emissioncharacteristics may be obtained without a substantial increase indriving voltage.

Then, an electron transport region may be disposed on the emissionlayer.

The electron transport region may include a hole blocking layer, anelectron transport layer, an electron injection layer, or anycombination thereof.

For example, the electron transport region may have a hole blockinglayer/electron transport layer/electron injection layer structure or anelectron transport layer/electron injection layer structure, but thestructure of the electron transport region is not limited thereto. Theelectron transport layer may have a single-layered structure or amulti-layered structure including two or more different materials.

Conditions for forming the hole blocking layer, the electron transportlayer, and the electron injection layer which constitute the electrontransport region may be understood by referring to the conditions forforming the hole injection layer.

When the electron transport region includes a hole blocking layer, thehole blocking layer may include, for example, BCP, Bphen, BAIq, or anycombination thereof, but embodiments of the present disclosure are notlimited thereto:

A thickness of the hole blocking layer may be in a range of about 20 Åto about 1,000 Å, for example, about 30 Å to about 300 Å. While notwishing to be bound by theory, it is understood that when the thicknessof the hole blocking layer is within these ranges, the hole blockinglayer may have improved hole blocking ability without a substantialincrease in driving voltage.

The electron transport layer may include BCP, Bphen, Alq₃, BAIq, TAZ,NTAZ, or any combination thereof:

In an embodiment, the electron transport layer may include at least oneof ET1 to ET25, but are not limited thereto:

A thickness of the electron transport layer may be in a range of about100 Å to about 1,000 Å, for example, about 150 Å to about 500 Å. Whilenot wishing to be bound by theory, it is understood that when thethickness of the electron transport layer is within the range describedabove, the electron transport layer may have satisfactory electrontransport characteristics without a substantial increase in drivingvoltage.

Also, the electron transport layer may further include, in addition tothe materials described above, a metal-containing material.

The metal-containing material may include a L₁ complex. The L₁ complexmay include, for example, Compound ET-D₁ (lithium 8-hydroxyquinolate,LiQ) or ET-D₂:

The electron transport region may include an electron injection layerthat promotes flow of electrons from the second electrode 19 thereinto.

The electron injection layer may include LiF, NaCl, CsF, L₁₂O, BaO, orany combination thereof.

A thickness of the electron injection layer may be in a range of about 1Å to about 100 Å, for example, about 3 Å to about 90 Å. While notwishing to be bound by theory, it is understood that when the thicknessof the electron injection layer is within the range described above, theelectron injection layer may have satisfactory electron injectioncharacteristics without a substantial increase in driving voltage.

The second electrode 19 is disposed on the organic layer 15. The secondelectrode 19 may be a cathode. A material for forming the secondelectrode 19 may be metal, an alloy, an electrically conductivecompound, or any combination thereof, which have a relatively low workfunction. For example, lithium (L₁), magnesium (Mg), aluminum (Al),aluminum-lithium (Al-L₁), calcium (Ca), magnesium-indium (Mg—In), ormagnesium-silver (Mg—Ag) may be used as a material for forming thesecond electrode 19. In an embodiment, to manufacture a top-emissiontype light-emitting device, a transmissive electrode formed using ITO orIZO may be used as the second electrode 19.

Hereinbefore, the organic light-emitting device has been described withreference to the FIGURE, but embodiments of the present disclosure arenot limited thereto.

Another aspect of the present disclosure provides a diagnosticcomposition including an organometallic compound represented by Formula1.

The organometallic compound represented by Formula 1 provides highluminescent efficiency. Accordingly, a diagnostic composition includingthe organometallic compound may have high diagnostic efficiency.

The diagnostic composition may be used in various applications includinga diagnosis kit, a diagnosis reagent, a biosensor, and a biomarker.

The term “C₁-C₆₀ alkyl group” as used herein refers to a linear orbranched saturated aliphatic hydrocarbon monovalent group having 1 to 60carbon atoms, and non-limiting examples thereof include a methyl group,an ethyl group, a propyl group, an iso-butyl group, a sec-butyl group, atert-butyl group, a pentyl group, an iso-amyl group, and a hexyl group.The term “C₁-C₆₀ alkylene group” as used herein refers to a divalentgroup having the same structure as the C₁-C₆₀ alkyl group.

The term “C₁-C₆₀ alkoxy group” as used herein refers to a monovalentgroup represented by —OA₁₀₁(wherein A₁₀₁ is the C₁-C₆₀ alkyl group), andnon-limiting examples thereof include a methoxy group, an ethoxy group,and an iso-propyloxy group.

The term “C₂-C₆₀ alkenyl group” as used herein refers to a hydrocarbongroup formed by including a carbon-carbon double bond in the middle orat the terminus of the C₂-C₆₀ alkyl group, and examples thereof includean ethenyl group, a propenyl group, and a butenyl group. The term“C₂-C₆₀ alkenylene group” as used herein refers to a divalent grouphaving the same structure as the C₂-C₆₀ alkenyl group.

The term “C₂-C₆₀ alkynyl group” as used herein refers to a hydrocarbongroup formed by including a carbon-carbon triple bond in the middle orat the terminus of the C₂-C₆₀ alkyl group, and examples thereof includean ethynyl group, and a propynyl group. The term “C₂-C₆₀ alkynylenegroup” as used herein refers to a divalent group having the samestructure as the C₂-C₆₀ alkynyl group.

The term “C₃-C₁₀ cycloalkyl group” as used herein refers to a monovalentsaturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, andnon-limiting examples thereof include a cyclopropyl group, a cyclobutylgroup, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group.The term “C₃-C₁₀ cycloalkylene group” as used herein refers to adivalent group having the same structure as the C₃-C₁₀ cycloalkyl group.

The term “C₂-C₁₀ heterocycloalkyl group” as used herein refers to amonovalent saturated monocyclic group having an N, O, P, Si, Se, S, orany combination thereof as a ring-forming atom and 1 to 10 carbon atoms,and non-limiting examples thereof include a tetrahydrofuranyl group, anda tetrahydrothiophenyl group. The term “C₂-C₁₀ heterocycloalkylenegroup” as used herein refers to a divalent group having the samestructure as the C₂-C₁₀ heterocycloalkyl group.

The term “C₃-C₁₀ cycloalkenyl group” as used herein refers to amonovalent monocyclic group that has 3 to 10 carbon atoms and acarbon-carbon double bond in the ring thereof and that has noaromaticity, and non-limiting examples thereof include a cyclopentenylgroup, a cyclohexenyl group, and a cycloheptenyl group. The term “C₃-C₁₀cycloalkenylene group” as used herein refers to a divalent group havingthe same structure as the C₃-C₁₀ cycloalkenyl group.

The term “C₂-C₁₀ heterocycloalkenyl group” as used herein refers to amonovalent monocyclic group that has an N, O, P, Si, Se, S, or anycombination thereof as a ring-forming atom, 1 to 10 carbon atoms, and acarbon-carbon double bond in its ring. Examples of the C₂-C₁₀heterocycloalkenyl group are a 2,3-dihydrofuranyl group, and a2,3-dihydrothiophenyl group. The term “C₁-C₁₀ heterocycloalkenylenegroup” as used herein refers to a divalent group having the samestructure as the C₂-C₁₀ heterocycloalkenyl group.

The term “C₆-C₆₀ aryl group” as used herein refers to a monovalent grouphaving a carbocyclic aromatic system having 6 to 60 carbon atoms, andthe term “C₆-C₆₀ arylene group” as used herein refers to a divalentgroup having a carbocyclic aromatic system having 6 to 60 carbon atoms.Non-limiting examples of the C₆-C₆₀ aryl group include a phenyl group, anaphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenylgroup, and a chrysenyl group. When the C₆-C₆₀ aryl group and the C₆-C₆₀arylene group each include two or more rings, the rings may be fused toeach other.

The term “C₇-C₆₀ alkylaryl group” as used herein refers to a C₁-C₆₀ arylgroup substituted with a C₁-C₅₄ alkyl group.

The term “C₁-C₆₀ heteroaryl group” as used herein refers to a monovalentgroup having an aromatic system that has an N, O, P, Si, Se, S, or anycombination thereof as a ring-forming atom, and 1 to 60 carbon atoms.The term “C₁-C₆₀ heteroarylene group” as used herein refers to adivalent group having an aromatic system that has an N, O, P, Se, S, orany combination thereof as a ring-forming atom, and 1 to 60 carbonatoms. Non-limiting examples of the C₁-C₆₀ heteroaryl group include apyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinylgroup, a triazinyl group, a quinolinyl group, and an isoquinolinylgroup. When the C₁-C₆₀ heteroaryl group and the C₁-C₆₀ heteroarylenegroup each include two or more rings, the rings may be fused to eachother.

The term “C₂-C₆₀ alkylheteroaryl group” as used herein refers to aC₁-C₆₀ heteroaryl group substituted with a C₁-C₆₀ alkyl group.

The term “C₆-C₆₀ aryloxy group” as used herein indicates —OA₁₀₂ (whereinA₁₀₂ is the C₆-C₆₀ aryl group), a C₆-C₆₀ arylthio group as used hereinindicates —SA₁₀₃ (wherein A₁₀₃ is the C₆-C₆₀ aryl group), and the term“C₇-C₆₀ arylalkyl group” as used herein indicates —A₁₀₄A₁₀₅ (whereinA₁₀₅ is the C₆-C₅₉ aryl group and A₁₀₄ is the C₁-C₅₄ alkylene group).

The term “C₁-C₆₀ heteroaryloxy group” as used herein refers to —OA₁₀₆(wherein A₁₀₆ is the C₂-C₆₀ heteroaryl group), the term “C₁-C₆₀heteroarylthio group” as used herein indicates —SA₁₀₇ (wherein A₁₀₇ isthe C₁-C₆₀ heteroaryl group), and the term “C₂-C₆₀ heteroarylalkylgroup” as used herein refers to —A₁₀₈A₁₀₉ (A₁₀₉ is a C₁-C₅₉ heteroarylgroup, and A₁₀₈ is a C₁-C₅₉ alkylene group).

The term “monovalent non-aromatic condensed polycyclic group” as usedherein refers to a monovalent group (for example, having 8 to 60 carbonatoms) having two or more rings condensed to each other, only carbonatoms as ring-forming atoms, and having no aromaticity in its entiremolecular structure. Examples of the monovalent non-aromatic condensedpolycyclic group include a fluorenyl group. The term “divalentnon-aromatic condensed polycyclic group” as used herein refers to adivalent group having the same structure as the monovalent non-aromaticcondensed polycyclic group.

The term “monovalent non-aromatic condensed heteropolycyclic group” asused herein refers to a monovalent group (for example, having 2 to 60carbon atoms) having two or more rings condensed to each other, an N, O,P, Si, Se, S, or any combination thereof and carbon atoms, asring-forming atoms, and no aromaticity in its entire molecularstructure. Non-limiting examples of the monovalent non-aromaticcondensed heteropolycyclic group include a carbazolyl group. The term“divalent non-aromatic condensed heteropolycyclic group” as used hereinrefers to a divalent group having the same structure as the monovalentnon-aromatic condensed heteropolycyclic group.

The term “C₅-C₃₀ carbocyclic group” as used herein refers to a saturatedor unsaturated cyclic group having, as a ring-forming atom, 5 to 30carbon atoms only. The C₅-C₃₀ carbocyclic group may be a monocyclicgroup or a polycyclic group.

The term “C₂-C₃₀ heterocyclic group” as used herein refers to asaturated or unsaturated cyclic group having, as a ring-forming atom, anN, O, Si, P, Se, S, or any combination thereof and 1 to 30 carbon atoms.The C₂-C₃₀ heterocyclic group may be a monocyclic group or a polycyclicgroup.

A substituent of the substituted C₁-C₆₀ alkyl group, the substitutedC₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, thesubstituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkylgroup, the substituted C₂-C₁₀ heterocycloalkyl group, the substitutedC₃-C₁₀ cycloalkenyl group, the substituted C₂-C₁₀ heterocycloalkenylgroup, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxygroup, the substituted C₆-C₆₀ arylthio group, the substituted C₇-C₆₀arylalkyl group, the substituted C₁-C₆₀ heteroaryl group, thesubstituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀ heteroarylgroup, the substituted C₁-C₆₀ heteroaryloxy group, the substitutedC₁-C₆₀ heteroarylthio group, the substituted C₂-C₆₀ heteroarylalkylgroup, the substituted monovalent non-aromatic condensed polycyclicgroup, and the substituted monovalent non-aromatic condensedheteropolycyclic group may be:

a deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, aC₂-C₆₀ alkynyl group, or a C₁-C₆₀ alkoxy group;

a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, ora C₁-C₆₀ alkoxy group, each substituted with deuterium, —F, —Cl, —Br,—I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyanogroup, a nitro group, an amidino group, a hydrazine group, a hydrazonegroup, a carboxylic acid group or a salt thereof, a sulfonic acid groupor a salt thereof, a phosphoric acid group or a salt thereof, a C₃-C₁₀cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, aC₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅),—Ge(Q₁₃)(Q₁₄)(Q₁₅), —B(Q₁₆)(Q₁₇), —P(═O)(Q₁₈)(Q₁₉), —P(Q₁₈)(Q₁₉), or anycombination thereof;

a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ arylgroup, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxygroup, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group, each unsubstituted orsubstituted with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenylgroup, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, aC₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—Ge(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), —P(═O)(Q₂₈)(Q₂₉), —P(Q₂₈)(Q₂₉), or anycombination thereof;

—N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅), —Ge(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇),—P(═O)(Q₃₈)(Q₃₉), or —P(Q₃₈)(Q₃₉); or

any combination thereof. For example, a CH₂CN group is a C₁ groupsubstituted with a nitrile.

Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁ to Q₃₉ in this disclosure mayeach independently be hydrogen; deuterium; —F; —Cl; —Br; —I; a hydroxylgroup; a cyano group; a nitro group; an amidino group; a hydrazinegroup; a hydrazone group; a carboxylic acid group or a salt thereof; asulfonic acid group or a salt thereof; a phosphoric acid group or a saltthereof; a C₁-C₆₀ alkyl group unsubstituted or substituted withdeuterium, a C₁-C₆₀ alkyl group, a C₆-C₆₀ aryl group, or any combinationthereof; a C₂-C₆₀ alkenyl group; a C₂-C₆₀ alkynyl group; a C₁-C₆₀ alkoxygroup; a C₃-C₁₀ cycloalkyl group; a C₂-C₁₀ heterocycloalkyl group; aC₃-C₁₀ cycloalkenyl group; a C₂-C₁₀ heterocycloalkenyl group; a C₆-C₆₀aryl group unsubstituted or substituted with deuterium, a C₁-C₆₀ alkylgroup, a C₆-C₆₀ aryl group, or any combination thereof; a C₆-C₆₀ aryloxygroup; a C₆-C₆₀ arylthio group; a C₇-C₆₀ arylalkyl group; a C₁-C₆₀heteroaryl group; a C₁-C₆₀ heteroaryloxy group; a C₁-C₆₀ heteroarylthiogroup; a C₂-C₆₀ heteroarylalkyl group; a monovalent non-aromaticcondensed polycyclic group; or a monovalent non-aromatic condensedheteropolycyclic group.

Hereinafter, a compound and an organic light-emitting device accordingto embodiments are described in detail with reference to SynthesisExample and Examples. However, the organic light-emitting device is notlimited thereto. The expression “‘A’ is used instead of ‘B’” used indescribing Synthesis Examples means that a molar equivalent of “A” wasidentical to a molar equivalent of “B”.

EXAMPLES Synthesis Example 1 (Compound 6)

Synthesis of Intermediate 6-3

2.4 grams (g) (0.006 millimoles (mmol), 1.2 equivalents, equiv.) ofIntermediate 2-2, 1.4 g (0.005 mmol, 1 equiv.) of Intermediate 1-1, 0.40g (0.001 mmol, 0.07 equiv.) of tetrakis(triphenylphosphine)palladium(0),and 2.0 g (0.015 mmol, 3 equiv.) of potassium carbonate were dissolvedin 20 milliliters (mL) of a solvent in which tetrahydrofuran (THF) anddistilled water (H₂O) were mixed at a ratio of 3:1, and the reactionmixture was refluxed for 12 hours. The reaction mixture obtainedtherefrom was cooled to room temperature, and the precipitate wasfiltered to obtain a filtrate. The filtrate was washed by using ethylacetate (EA)/H₂O and the crude product was purified by columnchromatography (gradient elution of EA/hexane (Hex) from 20% to 35%) toobtain 2.2 g (yield of 68%) of Intermediate 6-3. The obtained compoundwas identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₈H₅₃D₈N₃O m/z 823.5317, Found: 823.5319.

Synthesis of Compound 6

2.2 g (2.26 mmol) of Intermediate 6-3 and 1.1 g (2.26 mmol, 1.0 equiv.)of K₂PtCl₄ were dissolved in 40 mL of a solvent in which 30 mL of AcOHand 10 mL of H₂O were mixed, and the reaction mixture was refluxed for16 hours. The reaction mixture obtained therefrom was cooled to roomtemperature, and the precipitate was filtered. The precipitate wasdissolved again in MC and washed by using H₂O. The crude product waspurified by column chromatography (methylene chloride (MC) 40%, EA 1%,Hex 59%) to obtain 1.6 g (yield of 60%) of Compound 6. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₈H₅₁D₈N₃OPt: m/z 1016.4808, Found: 1016.4805.

Synthesis Example 2 (Compound 1)

Synthesis of Intermediate 1-3

Intermediate 1-3 1.2 g (yield of 65%) was obtained in the same manner asin the synthesis of Intermediate 6-3 of Synthesis Example 1, except thatIntermediate 1-2 was used instead of Intermediate 2-2. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₉H₅₆D₇N₃O: m/z 836.5411, Found: 836.5414.

Synthesis of Compound 1

Compound 1 1.0 g (yield of 68%) was obtained in the same manner as inthe synthesis of Compound 6 of Synthesis Example 1, except thatIntermediate 1-3 was used instead of Intermediate 6-3. The obtainedcompound was identified by mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₉H₅₄D₇N₃OPt: m/z 1029.4902, Found: 1029.4901.

Synthesis Example 3 (Compound 2)

Synthesis of Intermediate 2-3

Intermediate 2-3 2.1 g (yield of 70%) was obtained in the same manner asin the synthesis of Intermediate 6-3 of Synthesis Example 1, except thatIntermediate 2-1 was used instead of Intermediate 1-1. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₈H₅₃D₈N₃O: m/z 823.5317, Found: 823.5319.

Synthesis of Compound 2

Compound 2 1.84 g (yield of 71%) was obtained in the same manner as inthe synthesis of Compound 6 of Synthesis Example 1, except thatIntermediate 2-3 was used instead of Intermediate 6-3. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₈H₅₁D₈N₃OPt: m/z 1016.4808, Found: 1016.4809.

Synthesis Example 4 (Compound 3)

Synthesis of Intermediate 3-3

Intermediate 3-3 1.7 g (yield of 72%) was obtained in the same manner asin the synthesis of Intermediate 6-3 of Synthesis Example 1, except thatIntermediate 3-2 was used instead of Intermediate 2-2. The obtainedcompound was identified by Mass and HPLC analysis.

HRMS (MALDI) calcd for C₅₉H₆₃N₃O: m/z 829.4971, Found: 829.4973.

Synthesis of Compound 3

Compound 3 1.53 g (yield of 73%) was obtained in the same manner as inthe synthesis of Compound 6 of Synthesis Example 1, except thatIntermediate 3-3 was used instead of Intermediate 6-3. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₉H₆₁N₃OPt: m/z 1022.4462, Found: 1022.4461.

Synthesis Example 5 (Compound 4)

Synthesis of Intermediate 4-3

Intermediate 4-3 1.85 g (yield of 73%) was obtained in the same manneras in the synthesis of Intermediate 6-3 of Synthesis Example 1, exceptthat Intermediate 4-2 was used instead of Intermediate 2-2. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₉H₆₀D₃N₃O: m/z 832.5159, Found 832.52.

Synthesis of Compound 4

Compound 4 1.64 g (yield of 72%) was obtained in the same manner as inthe synthesis of Compound 6 of Synthesis Example 1, except thatIntermediate 4-3 was used instead of Intermediate 6-3. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₉H₅₈D₃N₃OPt: m/z 1025.4651, Found: 1025.4652.

Synthesis Example 6 (Compound 5)

Synthesis of Intermediate 5-3

Intermediate 5-3 2 g (yield of 68%) was obtained in the same manner asin the synthesis of Intermediate 6-3 of Synthesis Example 1, except thatIntermediate 5-1 and Intermediate 5-2 were used instead of Intermediate1-1 and Intermediate 2-2. The obtained compound was identified by Massand HPLC analysis.

HRMS (MALDI) calcd for C₅₈H₆₁N₃O: m/z 815.4815, Found: 815.4813.

Synthesis of Compound 5

Compound 5 1.73 g (yield of 70%) was obtained in the same manner as inthe synthesis of Compound 6 of Synthesis Example 1, except thatIntermediate 5-3 was used instead of Intermediate 6-3. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₅₈H₅₉N₃OPt: m/z 1008.4306, Found: 1008.4308.

Synthesis Example 7 (Compound 7)

Synthesis of Intermediate 7-3

Intermediate 7-3 1.8 g (yield of 69%) was obtained in the same manner asin the synthesis of Intermediate 6-3 of Synthesis Example 1, except thatIntermediate 7-2 was used instead of Intermediate 2-2. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₆₀H₅₉D₆N₃O: m/z 849.5504, Found: 849.5502.

Synthesis of Compound 7

Compound 7 1.65 g (yield of 75%) was obtained in the same manner as inthe synthesis of Compound 6 of Synthesis Example 1, except thatIntermediate 7-3 was used instead of Intermediate 6-3. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₆₀H₅₇D₆N₃OPt: m/z 1042.4995, Found: 1042.4996.

Synthesis Example 8 (Compound 8)

Synthesis of Intermediate 8-3

Intermediate 8-3 1.7 g (yield of 65%) was obtained in the same manner asin the synthesis of Intermediate 6-3 of Synthesis Example 1, except thatIntermediate 8-2 was used instead of Intermediate 2-2. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₆₄H₆₅N₃O m/z 891.5128, Found: 891.5127.

Synthesis of Compound 8

Compound 8 1.41 g (yield of 68%) was obtained in the same manner as inthe synthesis of Compound 6 of Synthesis Example 1, except thatIntermediate 8-3 was used instead of Intermediate 6-3. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₆₄H₆₃N₃OPt m/z 1084.4619, Found: 1084.4617.

Synthesis Example 9 (Compound 9)

Synthesis of Intermediate 9-3

Intermediate 9-3 2.1 g (yield of 63%) was obtained in the same manner asin the synthesis of Intermediate 4-3 of Synthesis Example 5, except thatIntermediate 9-1 was used instead of Intermediate 1-1. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₆₁H₆₀D₅N₃O m/z 860.5441 Found 860.5443.

Synthesis of Compound 9

Compound 9 1.77 g (yield of 69%) was obtained in the same manner as inthe synthesis of Compound 4 of Synthesis Example 5, except thatIntermediate 9-3 was used instead of Intermediate 4-3. The obtainedcompound was identified by Mass spectrum and HPLC analysis.

HRMS (MALDI) calcd for C₆₁H₅₈D₅N₃OPt m/z 1053.4933 Found 1053.4932.

Evaluation Example 1 Evaluation of Photoluminescence Quantum Yield(PLQY) and Radiative Decay Rate

CBP and Compound 1 were co-deposited at a weight ratio of 9:1 at avacuum pressure of 10⁻⁷ torr to manufacture a film having a thickness of40 nanometers (nm).

A PLQY of the film was evaluated by using a Hamamatsu Photonics absolutePL quantum yield measurement system including a xenon light source, amonochromator, a photonic multichannel analyzer, an integrating sphereand employing a PLQY measurement software (Hamamatsu Photonics, Ltd.,Shizuoka, Japan), and a PLQY of Compound 1 was confirmed. The results ofthis study are shown in Table 2.

A PL spectrum of the film was evaluated at room temperature by using aPicoQuant TRPL measurement system FluoTime 300 and a PicoQuant pumpingsource PLS340 (excitation wavelength=340 nm, spectral width=20 nm), awavelength of a main peak of the spectrum was determined, PLS340repeatedly measured the number of photons emitted from the film at thewavelength of the main peak due to a photon pulse (pulse width=500picoseconds, ps) applied to the film according to time based ontime-correlated single photon counting (TCSPC), thereby obtaining asufficiently fittable TRPL curve. T_(decay)(Ex) (decay time) of the filmwas obtained by fitting one or more exponential decay functions to theresult obtained therefrom, and the radiative decay rate that is areciprocal of T_(decay)(Ex) was calculated. The results are shown inTable 2. The function used for fitting is expressed by Equation 20, andthe greatest value of T_(decay) obtained from each exponential decayfunction used for fitting was taken as T_(decay)(Ex). At this time, abaseline or background signal curve was obtained by repeating the samemeasurement once more for the same measurement time as the measurementtime for obtaining the TRPL curve in a dark state (a state in which apumping signal applied to the predetermined film was blocked), and thebaseline or background signal curve was used for fitting as a baseline.

$\begin{matrix}{{f(t)} = {\sum\limits_{i = 1}^{n}\; {A_{i}\mspace{14mu} {\exp \left( {{- t}\text{/}T_{{decay},i}} \right)}}}} & {{Equation}\mspace{14mu} 20}\end{matrix}$

The measurement of the PLQY and the radiative decay time was performedon Compounds 2 to 9, and results thereof are shown in Table 2.

TABLE 2 Compound Radiative decay rate No. PLQY (%) (s⁻¹) 1 0.999 4.15 ×10⁵ 2 0.992 4.09 × 10⁵ 3 0.999 4.81 × 10⁵ 4 0.999 4.85 × 10⁵ 5 0.9994.99 × 10⁵ 6 0.999 4.93 × 10⁵ 7 0.998 4.90 × 10⁵ 8 0.999 4.83 × 10⁵ 90.999 4.16 × 10⁵ *s⁻¹ = reverse seconds

Referring to Table 2, it is confirmed that Compounds 1 to 9 have a highPLQY and a high radiative decay rate.

Evaluation Example 2: Evaluation of Horizontal Orientation Ratio

mCP and Compound 1 were co-deposited on a fused silica base layer(thickness of 1 mm) at a weight ratio of 92:8 in a vacuum depositionapparatus having a vacuum pressure of 1×10⁻⁷ torr to form Sample 1having a thickness of 30 nm (8 weight %), and Sample 1 was sealed withglass and glue in a nitrogen atmosphere. This procedure was repeated onCompounds shown in Table 3 to manufacture Samples 2 to 9.

Meanwhile, an angle-dependent PL measurement apparatus having astructure illustrated in FIG. 3 of Korean Patent Application No.10-2013-0150834, the content of which is incorporated herein in itsentirety by reference, was prepared. Detailed specifications are asfollows:

-   -   Excited light wavelength: 325 nm    -   Excited light supply source: He—Cd laser, Melles Griot    -   Excited light irradiation means: Optical fiber, diameter of 1        millimeter (mm), Thorlabs    -   Semi-cylindrical prism: Fused silica, diameter of 100 mm, length        of 30 mm    -   Emitted light detection means: Photomultiplier tube, Acton    -   Polarizer mounted on emitted light detection means: Linear        polarizer, Thorlabs    -   Recording apparatus: SpectraSense, Acton    -   Excited light incidence angle: θP=45°, θH=0°    -   Distance from sample to emitted light detection means (or radius        of moving path of emitted light detection means): 900 mm

Then, each of Samples 1 to 8 was fixed on a semi-cylindrical lens, and a325-nm laser was irradiated to emit light. The emitted light passedthrough a polarization film, and p-polarization light emission strengthwas measured with respect to 530-nm light of 90° to 0° while turning by1° with respect to the axis of the semi-cylindrical lens, to which thesample was fixed, by using a charge-coupled device (CCD).

p-Polarization light emission strength (first p-polarization lightemission strength) appearing when each Compound has a verticalorientation and p-polarization light emission strength (secondp-polarization light emission strength) appearing when each Compound hada horizontal orientation were calculated with respect to 0° to 90°. Theweights at which p-polarization light emission strength were calculatedby multiplying each weight by the first and second p-polarization lightemission strengths coinciding with the measured p-polarization lightemission strength, and the horizontal orientation ratios of Compoundsshown in Table 3 were measured. The results of this study are shown inTable 3. The angle-dependent PL spectrum was analyzed by using aclassical dipole moment regarded as dissipated power from a dipoleoscillating light emission from excitons.

TABLE 3 Horizontal orientation Sample No. Co-deposition material ratio(%) 1 mCP Compound 1 (8 weight %) 90% 2 mCP Compound 2 (8 weight %) 90%3 mCP Compound 3 (8 weight %) 88% 4 mCP Compound 4 (8 weight %) 88% 5mCP Compound 5 (8 weight %) 90% 6 mCP Compound 6 (8 weight %) 90% 7 mCPCompound 7 (8 weight %) 90% 8 mCP Compound 8 (8 weight %) 90% 9 mCPCompound 9 (8 weight %) 90% * weight % = percent by weight

Referring to Table 3, it is confirmed that Compound 1 to 9 haveexcellent horizontal orientation ratios, that is, excellent horizontaloptical orientation.

Example 1

As an anode, a glass substrate, on which ITO/Ag/ITO (70 Å/1,000 Å/70 Å)were deposited, was cut to a size of 50 mm×50 mm×0.5 mm, sonicated withiso-propyl alcohol and pure water each for 5 minutes, and cleaned byexposure to ultraviolet rays and ozone for 30 minutes. Then, the glasssubstrate was provided to a vacuum deposition apparatus.

2-TNATA was vacuum-deposited on the anode of the glass substrate to forma hole injection layer having a thickness of 600 Å, and4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) wasvacuum-deposited on the hole injection layer to form a hole transportlayer having a thickness of 1,350 Å.

CBP (host) and Compound 1 (dopant) were co-deposited on the holetransport layer at a weight ratio of 94:6 to form an emission layerhaving a thickness of 400 Å.

Then, BCP was vacuum-deposited on the emission layer to form a holeblocking layer having a thickness of 50 Å, Alq₃ was vacuum-deposited onthe hole blocking layer to form an electron transport layer having athickness of 350 Å, LiF was deposited on the electron transport layer toform an electron injection layer having a thickness of 10 Å, and MgAgwas deposited on the electron injection layer at a weight ratio of 90:10to form a cathode having a thickness of 120 Å, thereby completing anorganic light-emitting device having a structure of anode/2-TNATA (600Å)/NPB (1,350 Å)/CBP+Compound 1 (6 weight %) (400 Å)/BCP (50 Å)/Alq₃(350 Å) /LiF (10 Å)/MgAg (120 Å).

Examples 2 to 9 and Comparative Examples a to E

Organic light-emitting devices were manufactured in the same manner asin Example 1, except that Compound shown in Table 4 were each usedinstead of Compound 1 as a dopant in forming an emission layer.

Evaluation Example 3: Evaluation of Characteristics of OrganicLight-Emitting Devices

The driving voltage, current density, maximum quantum efficiency,roll-off ratio, full width at half maximum (FWHM), peak emissionwavelength, and lifespan of the organic light-emitting devicesmanufactured according to Examples 1 to 9 and Comparative Example A to Ewere evaluated by using a current-voltage meter (Keithley 2400) and aluminance meter (Minolta Cs-1000A), and results thereof are shown inTables 4 and 5. The roll-off ratio was calculated by Equation 30. Thelifespan (LT₉₉, at 3,500 nit) indicates an amount of time that elapsedwhen luminance was 99% of initial luminance (100%) and is expressed by arelative value (%).

roll off ratio={1−(efficiency (at 3,500 nit)/maximum luminescentefficiency)}×100%  Equation 30

TABLE 4 Maximum Roll- Dopant Driving Current quantum off compoundvoltage density efficiency ratio FWHM No. (V) (mA/cm²) (%) (%) (nm)Example 1 1 3.69 10 112 9 68 Example 2 2 3.72 10 102 6 68 Example 3 33.79 10 107 8 68 Example 4 4 3.79 10 109 9 67 Example 5 5 3.83 10 99 769 Example 6 6 4.60 10 108 10 70 Example 7 7 3.84 10 111 8 67 Example 88 3.80 10 114 7 67 Example 9 9 3.96 10 110 7 67 Comparative A 3.94 10 9410 68 Example A Comparative B 4.08 10 93 8 68 Example B Comparative C3.85 10 98 4 68 Example C Comparative D 3.90 10 88 8 67 Example DComparative E 4.39 10 88 17 64 Example E

TABLE 5 Dopant Peak emission Lifespan (LT₉₉) compound wavelength (at3,500 nit) No. (nm) a relative value (%) Example 1 1 521 115% Example 22 523 110% Example 3 3 521 113% Example 4 4 521 115% Example 5 5 526110% Example 6 6 525 130% Example 7 7 524 110% Example 8 8 527 180%Example 9 9 523 105% Comparative Example A 523  29% A ComparativeExample B 526  50% B Comparative Example C 523  60% C ComparativeExample D 520   3% D Comparative Example E 502   1% E

Referring to Tables 4 and 5, it is confirmed that the organiclight-emitting devices of Examples 1 to 9 have improved driving voltage,improved maximum quantum efficiency, and/or improved roll-off ratio, andalso have improved lifespan characteristics, as compared with those ofthe organic light-emitting devices of Comparative Examples A to E.

Since the organometallic compound may emit light having a relativelysmall FWHM and have excellent PLQY, excellent radiative decay rate, andexcellent horizontal orientation ratio, the organic light-emittingdevice including the organometallic compound may have improved drivingvoltage, external quantum efficiency, roll-off ratio, and lifespancharacteristics. In addition, since the organometallic compound hasexcellent phosphorescence characteristics, a diagnostic compositionincluding the organometallic compound may have high diagnosticefficiency.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While embodiments have been described with reference to the figures, itwill be understood by those of ordinary skill in the art that variouschanges in form and details may be made therein without departing fromthe spirit and scope of the present description as defined by thefollowing claims.

What is claimed is:
 1. An organometallic compound represented by Formula1:

wherein, in Formula 1, M is a transition metal, X₁ is O or S, wherein abond between X₁ and M is a covalent bond, X₂ to X₄ are eachindependently C or N, a bond between X₂ and M, a bond between X₃ and M,or a bond between X₄ and M is a covalent bond, and the other bonds of abond between X₂ and M, a bond between X₃ and M, and a bond between X₄and M are coordinate bonds, Y₁ and Y₃ to Y₅ are each independently C orN, a bond between X₂ and Y₃, a bond between X₂ and Y₄, and a bondbetween Y₄ and Y₅ is a chemical bond, ring CY₁ to ring CY₄ and ring CY₅₁are each independently a C₅-C₃₀ carbocyclic group or a C₂-C₃₀heterocyclic group, a cyclometalated ring formed by ring CY₅, ring CY₂,ring CY₃, and M is a 6-membered ring, T₁ is a single bond, a doublebond, *—N(R₅)—*′, *—B(R₅)—*′, *—P(R₅)—*′, *—C(R₅)(R₆)—*′,*—Si(R₅)(R₆)—*′, *—Ge(R₅)(R₆)—*′, *—S—*, *—Se—*′, * *, *—C(═O)—*′,*—S(═O)—*′, *—S(═O)₂—*, * C(R₅)=*′, *═C(R₅)—*′, *—C(R₅)═C(R₆)—*′,*—C(═S)—*′, or *—C≡C—*′, wherein * and *′ each indicate a binding siteto a neighboring atom, L₁ to L₄ and L₅₁ are each independently a singlebond, a C₅-C₃₀ carbocyclic group that is unsubstituted or substitutedwith an R_(10a) group, or a C₂-C₃₀ heterocyclic group that isunsubstituted or substituted with an R_(10a) group, b1 to b4 and b51 areeach independently an integer from 1 to 5, R₁ to R₆, R₅₁, and R₅₂ areeach independently hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a substituted or unsubstituted C₁-C₆₀ alkylgroup, a substituted or unsubstituted C₂-C₆₀ alkenyl group, asubstituted or unsubstituted C₂-C₆₀ alkynyl group, a substituted orunsubstituted C₁-C₆₀ alkoxy group, a substituted or unsubstituted C₃-C₁₀cycloalkyl group, a substituted or unsubstituted C₂-C₁₀ heterocycloalkylgroup, a substituted or unsubstituted C₃-C₁₀ cycloalkenyl group, asubstituted or unsubstituted C₂-C₁₀ heterocycloalkenyl group, asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₆-C₆₀ aryloxy group, a substituted or unsubstitutedC₆-C₆₀ arylthio group, a substituted or unsubstituted C₇-C₆₀ arylalkylgroup, a substituted or unsubstituted C₁-C₆₀ heteroaryl group, asubstituted or unsubstituted C₁-C₆₀ heteroaryloxy group, a substitutedor unsubstituted C₁-C₆₀ heteroarylthio group, a substituted orunsubstituted C₂-C₆₀ heteroarylalkyl group, a substituted orunsubstituted monovalent non-aromatic condensed polycyclic group, asubstituted or unsubstituted monovalent non-aromatic condensedheteropolycyclic group, —N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —Ge(Q₃)(Q₄)(Q₅),—B(Q₆)(Q₇), —P(═O)(Q₈)(Q₉), or —P(Q₈)(Q₉), c1 to c4, c51 and c52 areeach independently an integer from 1 to 5, A₅₁ is a C₄-C₆₀ alkyl group,A₅₂ is deuterium or a deuterium-containing C₁-C₆₀ alkyl groupunsubstituted or substituted with a C₃-C₁₀ cycloalkyl group, a1 to a4,a51, and a52 are each independently an integer from 0 to 10, providedthat the sum of a51 and a52 is 1 or more, a53 is an integer from 1 to10, two or more groups of a plurality of R₁ groups are optionally linkedto form a C₅-C₃₀ carbocyclic group that is unsubstituted or substitutedwith an R_(10a) group or a C₂-C₃₀ heterocyclic group that isunsubstituted or substituted with an R_(10a) group, two or more groupsof a plurality of R₂ groups are optionally linked to form a C₅-C₃₀carbocyclic group that is unsubstituted or substituted with an R_(10a)group or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group, two or more groups of a plurality ofR₃ groups are optionally linked to form a C₅-C₃₀ carbocyclic group thatis unsubstituted or substituted with an R_(10a) group or a C₂-C₃₀heterocyclic group that is unsubstituted or substituted with an R_(10a)group, two or more groups of a plurality of R₄ groups are optionallylinked to form a C₅-C₃₀ carbocyclic group that is unsubstituted orsubstituted with an an R_(10a) group or a C₂-C₃₀ heterocyclic group thatis unsubstituted or substituted with an R_(10a) group, two or moregroups of R₁ to R₆ are optionally linked to form a C₅-C₃₀ carbocyclicgroup that is unsubstituted or substituted with an R_(10a) group or aC₂-C₃₀ heterocyclic group that is unsubstituted or substituted with anR_(10a) group, R_(10a) is the same as described in connection with R₁, asubstituent of the substituted C₁-C₆₀ alkyl group, the substitutedC₂-C₆₀ alkenyl group, the substituted C₂-C₆₀ alkynyl group, thesubstituted C₁-C₆₀ alkoxy group, the substituted C₃-C₁₀ cycloalkylgroup, the substituted C₂-C₁₀ heterocycloalkyl group, the substitutedC₃-C₁₀ cycloalkenyl group, the substituted C₂-C₁₀ heterocycloalkenylgroup, the substituted C₆-C₆₀ aryl group, the substituted C₆-C₆₀ aryloxygroup, the substituted C₆-C₆₀ arylthio group, the substituted C₇-C₆₀arylalkyl group, the substituted C₁-C₆₀ heteroaryl group, thesubstituted C₇-C₆₀ arylalkyl group, the substituted C₁-C₆₀ heteroarylgroup, the substituted C₁-C₆₀ heteroaryloxy group, the substitutedC₁-C₆₀ heteroarylthio group, the substituted C₂-C₆₀ heteroarylalkylgroup, the substituted monovalent non-aromatic condensed polycyclicgroup, and the substituted monovalent non-aromatic condensedheteropolycyclic group is: deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H,—CDH₂, —CF₃, —CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitrogroup, an amidino group, a hydrazine group, a hydrazone group, acarboxylic acid group or a salt thereof, a sulfonic acid group or a saltthereof, a phosphoric acid group or a salt thereof, a C₁-C₆₀ alkylgroup, a C₂-C₆₀ alkenyl group, a C₂-C₆₀ alkynyl group, or a C₁-C₆₀alkoxy group; a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenyl group, a C₂-C₆₀alkynyl group, or a C₁-C₆₀ alkoxy group, each substituted withdeuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, ahydroxyl group, a cyano group, a nitro group, an amidino group, ahydrazine group, a hydrazone group, a carboxylic acid group or a saltthereof, a sulfonic acid group or a salt thereof, a phosphoric acidgroup or a salt thereof, a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀heterocycloalkyl group, a C₃-C₁₀ cycloalkenyl group, a C₂-C₁₀heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀ aryloxy group, aC₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, a C₁-C₆₀ heteroarylgroup, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀ heteroarylthio group, aC₂-C₆₀ heteroarylalkyl group, a monovalent non-aromatic condensedpolycyclic group, a monovalent non-aromatic condensed heteropolycyclicgroup, —N(Q₁₁)(Q₁₂), —Si(Q₁₃)(Q₁₄)(Q₁₅), —Ge(Q₁₃)(Q₁₄)(Q₁₅),—B(Q₁₆)(Q₁₇), —P(═O)(Q₁₈)(Q₁₉), —P(Q₁₈)(Q₁₉), or any combinationthereof; a C₃-C₁₀ cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, aC₃-C₁₀ cycloalkenyl group, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀aryl group, a C₆-C₆₀ aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀arylalkyl group, a C₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxygroup, a C₁-C₆₀ heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, amonovalent non-aromatic condensed polycyclic group, and a monovalentnon-aromatic condensed heteropolycyclic group, each unsubstituted orsubstituted with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃,—CF₂H, —CFH₂, a hydroxyl group, a cyano group, a nitro group, an amidinogroup, a hydrazine group, a hydrazone group, a carboxylic acid group ora salt thereof, a sulfonic acid group or a salt thereof, a phosphoricacid group or a salt thereof, a C₁-C₆₀ alkyl group, a C₂-C₆₀ alkenylgroup, a C₂-C₆₀ alkynyl group, a C₁-C₆₀ alkoxy group, a C₃-C₁₀cycloalkyl group, a C₂-C₁₀ heterocycloalkyl group, a C₃-C₁₀ cycloalkenylgroup, a C₂-C₁₀ heterocycloalkenyl group, a C₆-C₆₀ aryl group, a C₆-C₆₀aryloxy group, a C₆-C₆₀ arylthio group, a C₇-C₆₀ arylalkyl group, aC₁-C₆₀ heteroaryl group, a C₁-C₆₀ heteroaryloxy group, a C₁-C₆₀heteroarylthio group, a C₂-C₆₀ heteroarylalkyl group, a monovalentnon-aromatic condensed polycyclic group, a monovalent non-aromaticcondensed heteropolycyclic group, —N(Q₂₁)(Q₂₂), —Si(Q₂₃)(Q₂₄)(Q₂₅),—Ge(Q₂₃)(Q₂₄)(Q₂₅), —B(Q₂₆)(Q₂₇), —P(═O)(Q₂₈)(Q₂₉), —P(Q₂₈)(Q₂₉), or anycombination thereof; —N(Q₃₁)(Q₃₂), —Si(Q₃₃)(Q₃₄)(Q₃₅),—Ge(Q₃₃)(Q₃₄)(Q₃₅), —B(Q₃₆)(Q₃₇), —P(═O)(Q₃₈)(Q₃₉), or —P(Q₃₈)(Q₃₉); orany combination thereof; and Q₁ to Q₉, Q₁₁ to Q₁₉, Q₂₁ to Q₂₉, and Q₃₁to Q₃₉ are each independently hydrogen; deuterium; —F; —Cl; —Br; —I; ahydroxyl group; a cyano group; a nitro group; an amidino group; ahydrazine group; a hydrazone group; a carboxylic acid group or a saltthereof; a sulfonic acid group or a salt thereof; a phosphoric acidgroup or a salt thereof; a C₁-C₆₀ alkyl group unsubstituted orsubstituted with deuterium, a C₁-C₆₀ alkyl group, a C₆-C₆₀ aryl group,or any combination thereof; a C₂-C₆₀ alkenyl group; a C₂-C₆₀ alkynylgroup; a C₁-C₆₀ alkoxy group; a C₃-C₁₀ cycloalkyl group; a C₂-C₁₀heterocycloalkyl group; a C₃-C₁₀ cycloalkenyl group; a C₂-C₁₀heterocycloalkenyl group; a C₆-C₆₀ aryl group unsubstituted orsubstituted with deuterium, a C₁-C₆₀ alkyl group, a C₆-C₆₀ aryl group,or any combination thereof; a C₆-C₆₀ aryloxy group; a C₆-C₆₀ arylthiogroup; a C₇-C₆₀ arylalkyl group; a C₁-C₆₀ heteroaryl group; a C₁-C₆₀heteroaryloxy group; a C₁-C₆₀ heteroarylthio group; a C₂-C₆₀heteroarylalkyl group; a monovalent non-aromatic condensed polycyclicgroup; or a monovalent non-aromatic condensed heteropolycyclic group. 2.The organometallic compound of claim 1, wherein M is Pt, Pd, or Au. 3.The organometallic compound of claim 1, wherein A₅₁ is an n-butyl group,a sec-butyl group, an iso-butyl group, a tert-butyl group, an n-pentylgroup, a tert-pentyl group, a neo-pentyl group, an iso-pentyl group, asec-pentyl group, a 3-pentyl group, or a sec-iso-pentyl group,unsubstituted or substituted with a methyl group, an ethyl group, ann-propyl group, an iso-propyl group, an n-butyl group, a sec-butylgroup, an iso-butyl group, a tert-butyl group, an n-pentyl group, atert-pentyl group, a neo-pentyl group, an iso-pentyl group, a sec-pentylgroup, a 3-pentyl group, a sec-iso-pentyl group, or any combinationthereof, and A₅₂ is a deuterium-containing linear or branched C₁-C₂₀alkyl group unsubstituted or substituted with a C₃-C₁₀ cycloalkyl group,in which the linear or branched C₁-C₂₀ alkyl group is a methyl group, anethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, asec-butyl group, an iso-butyl group, a tert-butyl group, an n-pentylgroup, a tert-pentyl group, a neo-pentyl group, an iso-pentyl group, asec-pentyl group, a 3-pentyl group, or a sec-iso-pentyl group, eachunsubstituted or substituted with a methyl group, an ethyl group, ann-propyl group, an iso-propyl group, an n-butyl group, a sec-butylgroup, an iso-butyl group, a tert-butyl group, an n-pentyl group, atert-pentyl group, a neo-pentyl group, an iso-pentyl group, a sec-pentylgroup, a 3-pentyl group, a sec-iso-pentyl group, or any combinationthereof.
 4. The organometallic compound of claim 1, wherein a3 and a4are not 0, and a group represented by *-(L₃)_(b3)-(R₃)_(c3), and a grouprepresented by *-(L₄)_(b4)-(R₄)_(c4) are not hydrogen.
 5. Theorganometallic compound of claim 1, wherein a3 is not 0, and an*-(L₃)_(b3)-(R₃)_(c3) in a number of a3 satisfies Condition A andCondition B: Condition A L₃ is a single bond, Condition B R₃ ishydrogen, deuterium, —F, a cyano group, C₁-C₂₀ alkyl group, or a C₁-C₂₀alkoxy group; a C₁-C₂₀ alkyl group or a C₁-C₂₀ alkoxy group, eachsubstituted with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a cyano group, a C₁-C₁₀ alkyl group, a cyclopentyl group, a cyclohexylgroup, a cycloheptyl group, a cyclooctyl group, an adamantyl group, anorbornenyl group, a cyclopentenyl group, a cyclohexenyl group, acycloheptenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexylgroup, a bicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a(C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl group, a(C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀ alkyl)cyclooctyl group, a(C₁-C₂₀ alkyl)adamantyl group, a (C₁-C₂₀ alkyl)norbornenyl group, a(C₁-C₂₀ alkyl)cyclopentenyl group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a(C₁-C₂₀ alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentylgroup, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀ alkyl)bicyclo[2.2.2]octylgroup, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl group, aterphenyl group, or any combination thereof; or a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantylgroup, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, abicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, abicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group,a biphenyl group, or a terphenyl group, each unsubstituted orsubstituted with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a cyano group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀ alkylgroup, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, abicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a (C₁-C₂₀alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl group, a (C₁-C₂₀alkyl)cycloheptyl group, a (C₁-C₂₀ alkyl)cyclooctyl group, a (C₁-C₂₀alkyl)adamantyl group, a (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀alkyl)cyclopentenyl group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl group, a(C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀ alkyl)bicyclo[2.2.2]octylgroup, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl group, aterphenyl group, or any combination thereof.
 6. The organometalliccompound of claim 1, wherein a4 is not 0, and a group represented by*-(L₄)_(b4)-(R₄)_(c4) in a number of a4 satisfies Condition 1, Condition2, or combination thereof: Condition 1 An R₄ in a number of c4 is asubstituted or unsubstituted C₆-C₆₀ aryl group, a substituted orunsubstituted C₁-C₆₀ heteroaryl group, a substituted or unsubstitutedmonovalent non-aromatic condensed polycyclic group, or a substituted orunsubstituted monovalent non-aromatic condensed heteropolycyclic group,Condition 2 L₄ is not a single bond.
 7. The organometallic compound ofclaim 1, wherein a4 is not 0, and an *-(L₄)_(b4)-(R₄)_(c4) in a numberof a4 satisfies Condition 1(1), Condition 2(1), or combination thereof:Condition 1(1) An R₄ in a number of c4 is a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, an adamantylgroup, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group,a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, abicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, abicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group,a biphenyl group, or a terphenyl group, each unsubstituted orsubstituted with deuterium, —F, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂,a cyano group, a C₁-C₂₀ alkyl group, a deuterium-containing C₂-C₂₀ alkylgroup, a C₁-C₂₀ alkoxy group, a cyclopentyl group, a cyclohexyl group, acycloheptyl group, a cyclooctyl group, an adamantyl group, a norbornenylgroup, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenylgroup, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, abicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, a (C₁-C₂₀alkyl)cyclopentyl group, a (C₁-C₂₀ alkyl)cyclohexyl group, a (C₁-C₂₀alkyl)cycloheptyl group, a (C₁-C₂₀ alkyl)cyclooctyl group, a (C₁-C₂₀alkyl)adamantyl group, a (C₁-C₂₀ alkyl)norbornenyl group, a (C₁-C₂₀alkyl)cyclopentenyl group, a (C₁-C₂₀ alkyl)cyclohexenyl group, a (C₁-C₂₀alkyl)cycloheptenyl group, a (C₁-C₂₀ alkyl)bicyclo[1.1.1]pentyl group, a(C₁-C₂₀ alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀ alkyl)bicyclo[2.2.2]octylgroup, a phenyl group, a (C₁-C₂₀ alkyl)phenyl group, a biphenyl group, aterphenyl group, or any combination thereof, Condition 2(1) L₄ is abenzene group unsubstituted or substituted with deuterium, —F, —CD₃,—CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a cyano group, a C₁-C₂₀ alkyl group, adeuterium-containing C₂-C₂₀ alkyl group, a C₁-C₂₀ alkoxy group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup, an adamantyl group, a norbornenyl group, a cyclopentenyl group, acyclohexenyl group, a cycloheptenyl group, a bicyclo[1.1.1]pentyl group,a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.1]heptyl group, abicyclo[2.2.2]octyl group, a (C₁-C₂₀ alkyl)cyclopentyl group, a (C₁-C₂₀alkyl)cyclohexyl group, a (C₁-C₂₀ alkyl)cycloheptyl group, a (C₁-C₂₀alkyl)cyclooctyl group, a (C₁-C₂₀ alkyl)adamantyl group, a (C₁-C₂₀alkyl)norbornenyl group, a (C₁-C₂₀ alkyl)cyclopentenyl group, a (C₁-C₂₀alkyl)cyclohexenyl group, a (C₁-C₂₀ alkyl)cycloheptenyl group, a (C₁-C₂₀alkyl)bicyclo[1.1.1]pentyl group, a (C₁-C₂₀ alkyl)bicyclo[2.1.1]hexylgroup, a (C₁-C₂₀ alkyl)bicyclo[2.2.1]heptyl group, a (C₁-C₂₀alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀ alkyl)phenylgroup, a biphenyl group, a terphenyl group, or any combination thereof.8. The organometallic compound of claim 1, wherein a4 is not 0, and an*-(L₄)_(b4)-(R₄)_(c4) in a number of a4 satisfies Condition 3, Condition4, Condition 5, or combination thereof: Condition 3 R₄ in a number of c4is a substituted C₆-C₆₀ aryl group, Condition 4 L₄ is a C₅-C₃₀carbocyclic group substituted with an R_(10a) group, Condition 5 L₄ is aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group and R₄ is not hydrogen.
 9. The organometallic compound ofclaim 1, wherein a51 and a52 are each independently 0, 1, or 2, the sumof a51 and a52 is 1 or 2, and a53 is 1 or
 2. 10. The organometalliccompound of claim 1, wherein, in Formula 1, a group represented by

is a group represented by one of Formulae CY1(1) to CY1(8), a grouprepresented by

is a group represented by one of Formulae CY2(1) to CY2(4), a grouprepresented by

is a group represented by one of Formulae CY3(1) to CY3(24), and a grouprepresented by

is a group represented by one of Formulae CY4(1) to CY4(74):

wherein, in Formulae CY1(1) to CY1(8), CY2(1) to CY2(4), CY3(1) toCY3(24), and CY4(1) to CY4(74), X₂ to X₄, Y₁, L₁ to L₄, b1 to b4, R₁ toR₄, and c1 to c4 are each independently the same as described in claim1, X₃₁ is O, S, N(R₃₁), C(R₃₁)(R₃₂), or Si(R₃₁)(R₃₂), X₄₁ is O, S,N(R₄₁), C(R₄₁)(R₄₂), or Si(R₄₁)(R₄₂), L_(1a) and L_(1b) are eachindependently the same as described in connection with L₁ in claim 1,R_(1a) and R_(1b) are each independently the same as described inconnection with R₁ in claim 1, L_(3a) and L_(3b) are each independentlythe same as described in connection with L₃ in claim 1, R_(3a), R_(3b),R₃₁, and R₃₂ are each independently the same as described in connectionwith R₃ in claim 1, L_(4a) to L_(4d) are each independently the same asdescribed in connection with L₄ in claim 1, R_(4a) to R_(4d), R₄₁, andR₄₂ are each independently the same as described in connection with R₄in claim 1, *-(L₁)_(b1)-(R₁)_(c1), *-(L_(1a))_(b1)-(R_(1a))_(c1),*-(L_(1b))_(b1)-(R_(1a))_(c1), *-(L₂)_(b2)-(R₂)_(c2),*-(L₃)_(b3)-(R₃)_(c3), * (L_(3a))_(b3)-(R_(3a))_(c3),*-(L_(3b))_(b3)-(R_(3a))_(c3), *-(L₄)_(b4)-(R₄)_(c4),*-(L_(4a))_(b4)-(R_(4a))_(c4), *-(L_(4b))_(b4)-(R_(4a))_(c4),*-(L_(4c))_(b4)-(R_(4c))_(c4), and *-(L_(4d))_(b4)-(R_(4d))_(c4) are nothydrogen, wherein * indicates a binding site to a neighboring atom, inFormulae CY1(1) to CY1(8), *′ indicates a binding site to X₁ in Formula1, in Formulae CY2(1) to CY2(4), CY3(1) to CY3(24), and CY4(1) toCY4(74), *′ indicates a binding site to M in Formula 1, in FormulaeCY1(1) to CY1(8), * indicates a binding site to Y₃ in Formula 1, inFormulae CY2(1) to CY2(4), * indicates a binding site to ring CY1 inFormula 1, and *″ indicates a binding site to ring CY3 in Formula 1, inFormulae CY3(1) to CY3(24), *″ indicates a binding site to ring CY2 inFormula 1, and * indicates a binding site to T₁ in Formula 1, and inFormulae CY4(1) to CY4(74), * indicates a binding site to T₁ inFormula
 1. 11. The organometallic compound of claim 1, wherein, inFormula 1, a group represented by

is a group represented by Formula CY4-1 or CY4-2:

wherein, in Formulae CY4-1 and CY4-2, X₄, L₄, b4, R₄, and c4 are eachindependently the same as described in claim 1, Z₄₁ to Z₄₄ are eachindependently the same as described in connection with R₄ in claim 1, ′indicates a binding site to M in Formula 1, and indicates a binding siteto T₁ in Formula
 1. 12. The organometallic compound of claim 10,wherein, in Formula 1, a group represented by

is a group represented by Formula CY1 (1) or CY1 (6), a grouprepresented by

is a group represented by Formula CY2(1), a group represented by

is a group represented by Formula CY3(3), and a group represented by

is a group represented by Formula CY4(3), CY4(4) or CY4(16).
 13. Theorganometallic compound of claim 1, wherein a group represented by

in Formula 1 is a group represented by one of Formulae 51-1 to 51-32:

wherein, in Formulae 51-1 to 51-32, R₅₁, R₅₂, c52, A₅₁, and A₅₂ are eachindependently the same as described in claim 1, R₅₃ and c53 are eachindependently the same as described in connection with R₅₂ and c52 inclaim 1, c512 is an integer of 0 to 2, c513 is an integer of 0 to 3, andindicates a binding site to L₅₁.
 14. The organometallic compound ofclaim 1, wherein the organometallic compound is represented by Formula1-1 or 1-2:

wherein, in Formulae 1-1 and 1-2 M, X₁ to X₄, Y₁, Y₃ to Y₅, L₄, L₅₁, b4,b51, R₅₁, R₅₂, c51, c52, A₅₁, A₅₂, a51, a52 and a53 are eachindependently the same as described in claim 1, Z₁₁ to Z₁₄ are eachindependently the same as described in connection with R in claim 1, Z₂₁to Z₂₃ are each independently the same as described in connection withR₂ in claim 1, Z₃₁ to Z₃₃ are each independently the same as describedin connection with R₃ in claim 1, Z₄₁ to Z₄₄ are each independently thesame as described in connection with R₄ in claim 1, two or more groupsof Z₁₁ to Z₁₄ are optionally linked to form a C₅-C₃₀ carbocyclic groupthat is unsubstituted or substituted with an R_(10a) group or a C₂-C₃₀heterocyclic group that is unsubstituted or substituted with an R_(10a)group, two or more groups of Z₂₁ to Z₂₃ are optionally linked to form aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group, two or more groups of Z₃₁ to Z₃₃ areoptionally linked to form a C₅-C₃₀ carbocyclic group that isunsubstituted or substituted with an R_(10a) group or a C₂-C₃₀heterocyclic group that is unsubstituted or substituted with an R_(10a)group, two or more groups of Z₄₁ to Z₄₄ are optionally linked to form aC₅-C₃₀ carbocyclic group that is unsubstituted or substituted with anR_(10a) group or a C₂-C₃₀ heterocyclic group that is unsubstituted orsubstituted with an R_(10a) group, and R_(10a) is the same as describedin connection with R₁.
 15. The organometallic compound of claim 14,wherein Z₁₂, Z₁₄, Z₂₁ to Z₂₃, Z₃₁, Z₃₃ and Z₄₁ to Z₄₄ are eachindependently hydrogen, deuterium, —CH₃, or —CD₃.
 16. An organiclight-emitting device comprising: a first electrode; a second electrode;and an organic layer disposed between the first electrode and the secondelectrode, wherein the organic layer comprises an emission layer, and anorganometallic compound of claim
 1. 17. The organic light-emittingdevice of claim 16, wherein the first electrode is an anode, the secondelectrode is a cathode, the organic layer further comprises a holetransport region disposed between the first electrode and the emissionlayer and an electron transport region disposed between the emissionlayer and the second electrode, wherein the hole transport regioncomprises a hole injection layer, a hole transport layer, an electronblocking layer, or any combination thereof, and wherein the electrontransport region comprises a hole blocking layer, an electron transportlayer, an electron injection layer, or any combination thereof.
 18. Theorganic light-emitting device of claim 16, wherein the emission layercomprises the organometallic compound.
 19. The organic light-emittingdevice of claim 18, wherein the emission layer further comprises a host,and an amount of the host is larger than an amount of the organometalliccompound.
 20. A diagnostic composition comprising an organometalliccompound of claim 1.